OBSERVATIONS 
ON 
VENTILATION: 
SHEWING THE 
POSSIBILITY OF PRODUCING ATMOSPHERES 
COOL AS WE PLEASE, 
EVEN UNDER THE EQUATOR, 
WITH 
HINTS 
AS TO THE PREVENTION OF THE 
PLAGUE AND YELLOW FEVER. 
JOHN VALLANCE 
BY 
LONDON: 
PRINTED FOR BAYNES AND SON, 
FATERNOSTER ROW. 
1821, TO THE 
RIGHT HONOURABLE 
THE 
EARL OF CHICHESTER, 
As an evidence, that the interest he was 
pleased to express, and the efforts he was 
so good as to make on the subject, are 
gratefully remembered, the following Ob- 
servations are respectfully dedicated. PREFACE. 
On placing myself at the bar of public 
opinion, it may be permitted me to desire 
that the feelings with which I appear there 
should be seen. 
I approach that bar, under the influence 
of feelings, in some degree similar to those 
experienced by him of antiquity, who lived 
destitute of the power of speech, till the 
emotions excited on beholding the sword 
descending on his revered parent, overcame 
the impediment nature had interposed. 
Since, as with him, articulation was not, 
until an overpowering sentiment possessed 
him of it, so had it never been in me to 
have attempted the press, if the failure of 
every other method, by which, what ap~ 
pears to me an important subject could be 
rendered public, had not driven me to it. 
As therefore, it could not have been ex- 
pected of one who had but just received VI 
the power of speech, that his pronunciation 
should be correct, neither can it be matter 
of surprise that the diction of one who 
has before never used the pen but for 
epistolary purposes, should be defective; 
and also, as the errors and inelegancies 
into which he should fall, would be passed 
over as resulting from what had been his 
situation; so I trust, will those into which 
I have fallen, be regarded as more my 
misfortune, than my fault. Since, as 
doubting my capability, I have not ven- 
tured on the press, until every other method 
of making what I have to submit, public, 
had been unavailingly tried, and as the cer- 
tainty of the principles on which it is 
founded, leaves no alternative as to whe- 
ther or not the press should be ventured on; 
point blank as I stand exposed to the fire, 
even of the lightest critical artillery, yet 
can I not but hope, that as I did not, with- 
out first trying all possible means to avoid 
it, place myself there, it will be levelled at* 
me more in mercy than in judgment. 
And to render forbearance to the extent 
which will in this particular be necessary, as little irksome as possible, it has been my 
object to say no more, than the view which 
I conceive it essential to give of the subject, 
rendered indispensable. 
I have therefore entered no further, ei- 
ther on the manufacturing and mechanical 
practicability, or the general ways and 
means of what I propose, than the profess- 
ing myself capable of surmounting the mere 
difficulties of operation, absolutely required; 
though I am ready to enter on the minutia 
of the manufacturing and mechanical diffi- 
culties of the case, and to prove them per- 
fectly supcrable, whenever it may be neces- 
sary. OBSERVATIONS, 
SC. 
((Impossible” may not unaptly be termed, the nightmare of 
speculative philosophy; and impossibilities/’ the change- 
ful drapery in which the incubus is shrouded. Thus, the 
circumnavigation of the globe—the knowledge we have 
attained, as to the laws of planetary motion—our ability 
of rendering the dread bolt of heaven innocuous—and in- 
deed, the whole of the modern attainments of science, 
were once “impossible:” and the being, who, in those 
times had predicted the triumphs, w'hich man, by his mere 
native powers should obtain over the elements, had been 
deemed, worthy only of that fate, which the fable repre- 
sents the travelled horse to have received, for stating, that 
he had seen the torrent arrested in its course, and changed 
into a substance, immoveable as the rock of the desert. 
It is well known, that meetings of a pub- 
lic nature, whether for pleasure, business, 
or devotion, are subject to inconveniences, 
arising from the atmosphere of the build- 
ing in which they are held, becoming af- 
fected by the respiration of the people as- 
sembled ; and that the consequences of its 
becoming so affected, are always oppres- sive and unpleasant, sometimes serious, and 
occasionally fatal. It is also known, that 
ventilation, though it lessens these evils, 
does not prevent them ; for the reasons, that 
when the weather is hot, the provisions for 
it are insufficient to the carrying off the re- 
spired, and introducing fresh air, in suffi- 
cient quantity; and that when it is cold, the 
admission of fresh air, in sufficient quantity 
to prevent any accumulation of the re- 
spired and heated air, cannot be permitted, 
owing to its giving those with whom it 
comes in contact, colds, &c. 
It is well known, that these are the 
causes which bring on the distressing heats, 
and unhealthy atmospheres, to which pub- 
lic places are subject: and as the intensity 
of these inflictions varies with the weather, 
and is more or less distressing, as it is hot- 
ter or colder; and as the weather is what 
man cannot control—it is for these reasons 
universally supposed, that the evils we thus 
suffer under are inseparable from our state, 
and what we cannot set ourselves above, 
and be free from. 
But universal as this supposition is, it is 3 
erroneous; there being well-known princi- 
ples, by which, it is equally possible to, at 
all times, produce and maintain the tem- 
perature of the temperate zones, even un- 
der the equator, as it is to produce that 
temperature in the frigid zones by means 
of fire. 
It is known, that on the vaporization of 
liquids, their capacities for caloric are much 
increased—that by removing the atmo- 
spheric pressure, their conversion to vapour 
is much facilitated—that on combining 
with this, Professor Leslie's method of con- 
densing vapour and keeping up the effect 
of the vacuum by means of absorbents, 
evaporation may be caused to take place 
even from ice—and that in consequence, 
caloric may be abstracted to an extent, 
many degrees lower than that required for 
the congelation of mercury, or 39° below 
zero. 
It is also known, that the capacities of 
gases for caloric are variable—that these ca- 
pacities may be decreased, or increased, by 
the addition, or removal of pressure—that, 
if subjected to condensation, a portion of 4 
their latent caloric, passes from its state of 
latency, to that of free, sensible caloric*— 
and, that on being released from this conden- 
sation to the state they were before in, they 
will absorb, and render latent, a quantity 
of caloric, equal to that which the conden- 
sation had, as it were, expressed from them. 
Now, by availing ourselves of and combin- 
ing these principles, climate may be so ef- 
fectually counteracted, as for it to be as 
much mere matter of volition, whether the 
temperatures of the temperate zones, shall 
be produced under the line, as the posses- 
sion of fuel, &c. would render it dependent 
on the will, whether those temperatures, 
# “ The gaseous substances are so loosely constituted, that 
a difference in their composition, is sufficient, to alter mate- 
rially, their intimate properties. Thus, common air, on be- 
ing condensed thirty times, has its capacity for heat, reduced 
to one half; and, if suddenly compressed, to twenty times its 
ordinary density, it will disengage so much heat, as to shew 
an elevation of temperature, equal to 900° by Fahrenheit’s 
scale, and sufficient for the inflammation of most bodies. 
On this property, is founded a pretty contrivance, lately 
made in France, for procuring a light—the stroke of a small 
condensing syringe being employed, to set on fire a bit of 
tinder.”—Leslie, on the Relations of Air, to Heat, and 
Moisture. should be produced within the frigid zones. 
Since, if air be condensed sufficiently to 
change a portion of its latent caloric, from 
the state of latency, to that of free, sensible 
caloric—if, in this condensed state, it be 
reduced in temperature, as the availing our- 
selves of Leslie's method of producing arti- 
ficial cold will enable our doing—and then 
suffered to mingle itself with a quantity of 
uncondensed air, which is being injected 
into any building, caloric would be absorb- 
ed, and rendered latent by it, and the tem- 
perature of the uncondensed portion con- 
sequently lowered, according to the relative 
states and quantities of the two portions. 
All therefore, that it is necessary to do, 
to produce whatever temperature might be 
desired, wdiether in the temperate or torrid 
zones, is to operate in this manner to a suf- 
ficient extent, and any building it might be 
wished to ventilate, could be supplied with 
an atmosphere, cooled to whatever degree 
habit, or climate, might render desirable, be 
the weather hot as it may: and, as the scale, 
on wffiich Leslie's method of producing ar- 
tificial cold may be acted upon, is, notwith- 
standing the opinion which prevails to the 6 
contrary, coextensive with our manufactur- 
ing capabilities, and as these are vastly more 
than sufficient for any purposes connected 
with the subject before us, and also, as I shall 
be able to prove the mechanical difficulties 
of the case much more easily superable than 
may at first be supposed, the means of sup- 
plying public assemblages, wherever situat- 
ed, with atmospheres of whatever tempera- 
ture might be desired, are indubitably in our 
hands, provided we choose but to make use 
of them. Since, as power and pneumatic 
apparatus give these means, and as our ma- 
nufacturing and mechanical capabilities, 
possess us of both, to extents almost infi- 
nitely beyond what would be required, the 
question becomes one of expediency merely, 
and the only decision necessary, whether we 
will, or will not, be at the expense of so coun- 
teracting the excessive heat, which is, within 
the tropics constantly, and without them 
occasionally experienced, as to produce in 
public buildings, whatever temperature ha- 
bit and situation may render agreeable. 
This is the only question ; and though no- 
thing but the actual application of the prin- 
ciple on a practical scale, will enable this 7 
question’s being correctly replied to; yet, as 
there are well-known circumstances, which 
put it in our power to obtain a sufficiently 
close approximation to the means required 
to produce these temperatures, to shew it 
in every way practicable, the subject may 
be entered upon free from any other un- 
certainty, than that the amount of the 
means necessary to produce effects we 
might desire, may be underrated. 
The circumstances to which I allude, as 
putting it in our power to obtain this ap- 
proximation, are, collectively, the whole of 
the occurrences, by which the theory of the 
capacities of gases for caloric, is confirmed; 
but more particularly, that experiment of 
Darwin's,* by which he found that air, on 
liberation from a condensation of about an 
atmosphere, to the common atmospheric 
pressure, absorbed caloric to an extent 
which reduced the thermometer 4°—and 
the phenomena, attending the emission of 
condensed air, from the fountain of Hiero, 
in the mines of Chemnitz—which are, that 
on the liberation of air from a condensation 
* Philosophical Transactions, voi, 78. 8 
of barely eight atmospheres, caloric is ren- 
dered latent to an extent, sufficient for the 
instantaneous production of both snow and 
ice.* 
From these circumstances it is seen, that 
on the liberation of air (after the caloric 
which the condensation had rendered free, 
had been carried off, and the condensed 
air reduced to the temperature of the atmo- 
sphere) from a state of condensation to the 
atmospheric pressure, caloric is absorbed 
and rendered latent, to, in the one case a 
very sensible, and in the other, to a very 
considerable degree. 
By, therefore, operating in this man- 
ner—condensing air, to the extent, we will 
say, of ten atmospheres—enclosing the ves- 
sel (a cylinder, placed vertically) it is re- 
# “ The striking phenomena observed in the fountain of 
Hiero, constructed at the mines of Chemnitz, in Hungary, 
afford the best example, of the production of cold, by rare- 
faction. In this engine, the air in a large vessel, is com- 
pressed by a column of water, 260 feet in height: on open- 
ing a stop-cock, it rushes out with great violence, and in ex- 
panding, the watery vapour which existed in it, is not only 
deposited, but is congealed, falling like snow, or adhering 
in icicles, to the aperture of the stop-cock. (Philosophical 
Transactions-.”)—M array’s Chemistry. 9 
ceived in, in another—percolating water, 
which has (as may by Leslies method ea- 
sily be done) previously being cooled to 32°, 
upon this receiving cylinder, so as for it to 
be constantly wet on the whole of its outer 
surface, and consequently, under similar 
circumstances with thermometer bulbs, 
when mercury is frozen in them by eva- 
poration on the Professor's principle—caus- 
ing this water to carry off the liberated ca- 
loric of the condensed air, by producing 
a vacuum in the outer cylinder, and in con- 
sequence, permiting the water to pass into 
vapour even after it becomes frozen, and 
has coated the enclosed cylinder with ice— 
and then, preventing any diminution of the 
effect of the vacuum, by condensing the va- 
pour by sulphuric acid—as, by operating 
in a way, which, though somewhat different 
from this in method, is similar in effect, 
mercury may be easily frozen, there can I 
think be no doubt, but that by doing thus, 
the condensed air might be cooled to at 
least zero ;* and from the instances I have 
*c< But after the water has all become solid ice, the cir- 
cle of evaporation, and subsequent absorption, is still main- 10 
referred to it is equally evident, that on li- 
beration from this condensation, the capa- 
city of the so-treated air, would be increas- 
ed to an extent which would reduce its 
temperature much lower. How much, can- 
not be said, though (inferring from those 
instances) it would doubtless be many de- 
grees lower. 
If, therefore, when the atmospheric tem- 
perature was 85°, air were treated thus to an 
extent which would render it 27° below 
zero on liberation from the condensation, 
and then admitted to mingle itself with un- 
condensed air in the proportion of a fourth, 
it would absorb, and render latent caloric, 
sufficient to reduce the temperature of the 
mixed portion to 57°, below which, it 
would not perhaps be desirable to have 
any building when the external atmosphere 
was 85°. 
I am aware it will be urged, that against 
tained. A minute film of ice, abstracting from the internal 
mass, a redoubled share of heat, passes, by invisible transi- 
tions, successively into the state of water, and of steam, 
which, dissolving in the thin, ambient air, is conveyed to the 
acid, where it again assumes the liquid form.”—Leslie— 
Relations, &c. 11 
the method of procedure which I have re- 
ferred to, there is a fatal objection, owing 
to the limit, as to magnitude of application 
which Mr. Leslie has found to take place, 
whenever any portion of water was situated 
at more than a few inches’ distance from 
the acid ;* a circumstance, which, were the 
operation attempted on the scale that would 
be necessary, to produce any effective re- 
sult as to ventilation, could not, it will be 
said, be avoided. But the difficulty as to 
largely acting on the Professor’s principle, 
which this at first appears to interpose, 
may, by a variation of process, be both 
so obviated, as to admit of operat- 
ing on whatever scale, our manufacturing 
# u But though the freezing of water is always performed 
to the best advantage in a large apparatus, a limit will soon 
occur to the scale of magnitude. Since, as the efficacy of 
the process, depends on the quick circulation, maintained 
between the opposite exhaling, and absorbing surfaces, and 
consequently, on their close proximity, the very extent of 
those surfaces, must have a tendency, to retard, and enfeeble 
their operation. Accordingly, when the earthen pan is un- 
usually wide, the central portion of its water, being most 
distant from the acid, seldom becomes firmly congealed.” 
Leslie—Relations, &c. 12 
capabilities will enable our constructing 
apparatus, and so as to produce a great- 
ly increased energy of action: since, if, 
instead of following the usual course, of 
placing the absorbent acid under, and 
consequently (even when refrigeration on 
the smallest scale is effected by this pro- 
cess) at some little distance from the cen- 
tral portion of the water, I follow the prin- 
ciple on which the outside of the inner cy- 
linder (or receiver) is moistened, i. e. put 
around it (vertically) a cylinder, or rather 
cage, composed of strips of lead, an inch 
wide by an eighth thick, placed edgeways 
towards the receiver, and each half an inch 
apart—which cage is so much larger than 
the receiver, as for there to be a space of 
an inch, or more or less, as experience may 
shew best, between them—and then so ar- 
range, as that the whole surface of the 
strips composing this cage, are, by a pecu- 
liar method of affusing it on the tops of 
them, constantly covered with a thin sur- 
face of sulphuric acid; if the process is 
thus (as may easily be done) arranged, not 
only will the preventative as to magnitude 13 
of operation to which I have referred, be 
obviated, but also will a far more intense 
action take place, owing, both to the 
evaporating, and absorbing surfaces, being 
thus brought into more direct communi- 
cation, than it is any how else possible to 
bring them ; and also, to the great increase 
of absorbent surface (as many times that 
of the water, as we please) that may thus 
be exposed : which intensity of action may 
be increased, until the two surfaces are 
brought so near together, as for the radia- 
tion of caloric from the outer, to be equal 
to the effect of evaporation from the inner 
surface. This, therefore, is the course I 
propose following; and as there is no diffi- 
culty, as to manufacturing condensing, and 
exhausting apparatus, on whatever scale 
of magnitude may be required, there are 
certainly no physical impossibilities, to the 
adoption of the plan. 
Now, assuming that a condensation of ten 
atmospheres, will be sufficient to reduce the 
temperature of the air to 27° below zero on 
its emission from the condenser, it is easy to 
tell what would be the power required, to 
produce and maintain in any building, an 14 
atmosphere tem. 57°, when the external 
air was 85°; since, as a steam engine of 
the power of one horse, can (calculating on 
the established relations between animate 
and inanimate power) be proved capable 
of condensing to a degree equal to ten at- 
mospheres, 25 gallons of air per minute, 
whatever quantity of condensed air might 
be required, divided by 25, gives the power 
necessary to condense it. On the suppo- 
sition, therefore, that it were the question, 
“ What power would be required to supply 
the two Houses of Parliament, or either 
Drury Lane or Covent Garden theatres— 
the former with each 500, and the latter 
with each 5000 gallons of air per minute, 
tem. 57°, when the atmosphere was 85° ?” 
(1000 or 5000) 4 25, shews, that in the 
one case a power equal to 10, and in the 
other to 50 horses, would be required; a 
mean, which, when reduced as the method 
of operation I have arranged admits, will 
become scarcely a question. As, therefore, 
it may be seen very evidently, and as I 
have it in my power to shew it very easily 
practicable, so to operate on air, as to sup- 
ply any building, under any parallel of la- titude, and at any time of the year, with 
an atmosphere of whatever temperature 
we please, I may proceed to state how 
it will be best to do it, and by what 
means the process may be so facilitated, 
as to produce the saving of power I have 
referred to. 
As to the first consideration, 46 How it 
will be best to do it.” 
As mechanical power must be made use 
of, both for the purpose of condensation, 
and to produce the vacuum by means of 
which the condensed air is to be cooled; 
and as the additional power which would 
be required for that purpose is next to no- 
thing,* it would (independent of the neces- 
sity there is for it) almost become matter 
of course, that the uncondensed air, instead 
of entering spontaneously, should be in- 
jected into the place to be ventilated. By 
* The injecting (as would be required for ventilation— 
not under the resistance opposed in the air cylinders of blast 
furnaces) even 100,000 gallons of merely fresh air per 
minute, would not be a difficult operation; so that the 
power which would be required, for the quantities I have 
referred to, is not worthy notice. means of blast cylinders (so arranged as to 
prevent the air having the least smell im- 
parted to it, or being in any way deterio- 
rated) this, therefore, would be done, and 
the air caused so to enter the place, as to be 
imperceptibly, and without either gusts or 
currents, distributed over the floor; whence 
it would gradually rise towards, and pass oft’ 
by, the ventilator. Before, however, it en- 
tered the place, the condensed air would 
(from a kind of insulated chamber, in which 
it had previously expanded, so as for its 
moisture to have been congealed and pre- 
cipitated) be emitted into, and caused to 
mingle with it; and its temperature conse- 
quently be lowered, according as the con- 
densation and refrigeration of that air regu- 
lated ; and as the method of condensation 
is also so arranged, as to prevent that air 
having any oleaginous, or other effluvium 
imparted to it, as is the case with air con- 
densed in the common way, nothing ob- 
jection al can arise on that particular. Such 
is the course taken with the uncondensed 
air—merely to inject it imperceptibly, and 
free from effluvia, into the place. 17 
With the condensed air, I proceed as fol- 
lows. Instead of condensing it as com- 
monly done, by a mere equi-potent pres- 
sure, I take advantage of the inequality of 
the resistance it opposes to a piston, to 
bring gravitation and momentum into 
action, and produce a very great increase 
of effect thus— 
If air were to be condensed in the large 
way (whether by horses, a steam engine, or 
other means of mechanical power) ac- 
cording to any of the methods hitherto fol- 
lowed, effects, equal only to the power ex- 
erted would be brought about; that is, a 
condensation, proportioned only to the 
force with which the power pressed down 
the piston of the condensing cylinder, would 
be produced; and, supposing that the area 
of this cjdinder were equal to ten inches, 
and that the piston were forced down by a 
power equal to 1500 lbs. a condensation of 
ten atmospheres would take place; and 
corresponding with this, would be the re- 
sult of the application of any greater power; 
that is, the effect produced would be pro- 
portional to the power exerted, and no 18 
more. But, if, instead of operating in this 
manner, I arrange the following method of 
operation; that is, instead of employing the 
power of the engine, to press down the piston 
of the condensing cylinder, I make it raise 
it up ; and if (loading the piston rod at top 
with the 1500 lbs.) when the piston is at 
the top of the cylinder, the machinery by 
which it is raised lets it fall, as is done by 
the weight, driver, ram, or whatever it is 
called, employed for driving piles, it is evi- 
dent, that the effect produced, would be 
greater than the power exerted, owing to 
the air beneath the piston admitting the 
weight to acquire very considerable mo- 
mentum, before it became sufficiently con- 
densed to oppose any effective resistance 
to it—that a condensation greater than ten 
atmospheres would be brought about, in 
consequence of this momentum—and that 
this increase of effect, would be propor- 
tioned to the height from which the weight 
falls, that is, to the length of the condens- 
ing cylinder. This, therefore, is the prin- 
ciple, of the course of operation I propose. 
Having arranged a method of construe- 19 
tion which admits it, I purpose having the 
condensing cylinders ten, twenty, thirty, 
or more feet long; and then, loading the 
pistons of these cylinders, with weights pro- 
portioned to the condensation required, 
and employing the machinery by which 
they are driven, to raise them up instead of 
pressing them down, to let them fall from the 
tops of the cylinders, when the momentum 
they would acquire in falling would so in- 
crease the effect produced,, as to render it 
a (comparatively) very easy thing to con- 
dense air to whatever extent may be re- 
quired. How easy may be inferred thus— 
A body, falling from the height of thirty 
feet, acquires I find, momentum to an ex- 
tent, which will give it percussive effect, 
sufficient to cause it (though not to any 
height, yet very perceptibly—the eighth of 
an inch for instance) to raise sixty times its 
own weight. Now, owing to air possess- 
ing the property of favouring the method 
of condensation I point out, by opposing, 
at first, no resistance to the descent of the 
piston—a resistance of only one tenth the 
weight (when it is equal to ten atmospheres 
per inch) the piston is loaded with, when 20 
that weight has fallen half the distance it 
has to fall—a resistance of barely one third 
that weight, when it has descended three 
fourths—a resistance but little more than 
three fourths, when the weight has descend- 
ed seven eighths of its distance—and a re- 
sistance equal to the weight itself, not be- 
fore it has descended the whole distance, 
through which the piston, were it forced 
down by machinery of any kind would 
have to descend ; owing to this property's 
thus admitting momentum's being acquir- 
ed, the method of condensation I point out, 
will produce effects greater than what would 
be produced by condensing in any other 
way, according to the degree in which the 
length of the condensing cylinder allows 
the weight to acquire momentum; and, 
though, owing to the difference between 
the momentum of a weight which has only 
to displace the air through which it falls, 
and that which is counteracted by the con- 
stantly increasing opposition of the air con- 
fined beneath the piston it forces down, this 
effect will not be increased in any sixty fold 
degree, yet, as in consequence of my having 
so arranged the method of operation with 21 
these pistons, as, while it does (as to any 
counteraction of effect) entirely away with 
friction between them and the cylinders, ren- 
ders totally impossible the escape of any con- 
densed air by them, the effect would doubt- 
less be increased in a manifold degree, I 
consider, that in calculating on only a quad- 
rupled increase of effect (that is, either the 
same condensation by one fourth the power, 
or four times the quantity by the same 
power) from this method of operation, I 
stop greatly short of the extent to which I 
might go. In saying, therefore, that in- 
stead of engines of 10 and 50 horses* power, 
being required to supply the Houses of Par- 
liament with 1000, or either Drury Lane 
or Covent Garden theatres with 5000 gal- 
lons of air per mibute, tem. 57°, when the 
atmosphere was 85°, it may be expected that 
engines of—-in the one case only 2i, and in 
the other only 12i horses’ power (the va- 
cuum for cooling the air, being so easily 
produced as not to be worth notice) would 
be required, I say, what may cause the 
practicability of the question in point 
of power, to be considered as sufficiently evident, even supposing me to have greatly 
overrated the effect of the method of con- 
densation I point out, and that the power 
required, should be twice or thrice as great 
as I have stated it.* 
Having thus (which is all that I deem it 
necessary to do here) sufficiently illustrated 
the principle, to give a general idea of the 
course to be taken, and means required for 
the purpose, I may turn to the advantages 
that would be derived from it. 
And taking them seriatim, that which I 
deem its greatest, so far as relates to con- 
venience merely, is the effect it will have 
as to the comfort and health of the Bench 
and the Bar. By the other classes of so- 
ciety, heated and deteriorated atmospheres 
are only occasionally, and then but for short 
periods experienced. But by those who 
preside and conduct in the courts of judi- 
* It may be as well to observe, that though, for convex 
nience of illustration, I have referred to the pistons as what 
the weights would operate upon, yet that, in point of fact, 
the reverse is the case : the course of operation being to 
raise and let fall the cylinders, instead of the pistons—in two 
words, the charging syringe of the air-gun, on a large scale. 23 
cature, the evil is experienced to a degree 
which only such as have undergone what a 
long trial, a crowded court, and hot weather 
inflict, can conceive. 
Not that it is not bad enough, in either 
of the Houses of Parliament. But, as be- 
tween the assemblages which convene in 
them, and the heterogeneous mass of a 
Court House, there is the great difference 
produced by clean linen, constant and 
copious personal ablution, and polished 
habits, the worst atmospheres experi- 
enced there, fall far short of those of the 
other. 
And, indeed, there is but one thing that 
I can conceive as worse, than the heated, 
mephitic vapour, sometimes encountered 
on entering the criminal courts—-particular- 
ly during any trial interesting to the lower 
classes; and that is, the atmosphere of the 
hold of a slave-ship. This, and this alone I 
can conceive, as worse than the surcharged, 
sickening atmosphere, of a crowded, cri- 
minal court. Now, from the whole of this, 
may both the Bench and Bar be relieved 
by the process I have described; and the courts (both metropolitan and provincial) 
be kept so pleasantly and healthily venti- 
lated, and (both in summer and winter—as 
will be exemplified in the course of the 
work) of so uniform and agreeable a tem- 
perature, as shall not only be of incalculable 
benefit, to the health of the dignified and 
learned characters, who preside, and lead in 
them, but also, shall materially conduce to 
the comfort of such of the magistracy and 
gentry of counties, as by either a sense of 
duty, or other circumstances, may be caus- 
ed to attend them; and this independent of 
the relief which juries, attorneys, and the 
public, would experience. 
This, I consider, as the principal benefit 
we may derive from what I propose. 
That which ranks next, must, of course, 
be the advantage which would result to the 
members, both of the upper and lower 
Houses of Parliament, from their atmo- 
spheres being rendered constantly tempe- 
rate and salubrious, as they may be, whe- 
ther the debates are long or short, the 
blouses full or empty, or the sessions in Ja- 
nuary or July ; and, had the Upper House, 25 
been then provided with the arrangements 
I have been describing, it is sufficiently evi- 
dent, that the whole, both of what the noble 
members, and those whose duty it was to 
attend them underwent, during the painful 
investigation of last summer, might have 
been prevented, and the building kept so 
uniformly temperate, as would have ren- 
dered the mere act of attending the inquiry, 
a very agreeable relief from the heat of the 
weather, instead of the parboiling it was. 
Following (on account of the infrequency 
of their occurrence) this, are the Levees, and 
Drawing-rooms; both of which may be kept 
free, from what occasionally inflicts on the 
Majesty and Dignity, the Beauty and De- 
licacy of the nation, the whole of the preli- 
minary symptoms of the Black-Hole sa- 
crifice. 
Succeeding these, are the theatres, Al- 
mack’s, and other places of public amuse- 
ment; the whole of which may be supplied 
with atmospheres, uniformly temperate and 
salubrious, and kept constantly of a plea- 
sant temperature, whether they are crowded 
to excess, or empty. 
After these come the residences of the 26 
nobility, the leaders of the “ haut ton,” &c. 
the whole of the reception apartments of 
which, may be kept of whatever tempera- 
ture they please at all times of the year, be 
their parties numerous as they may. 
Next come confectioners" shops, hotels, 
taverns, &c. &c. which may all be accom- 
modated with means of procuring atmo- 
spheres so cool and pleasant during hot 
weather, as shall cause them to be much 
resorted to as agreeable resting and re- 
freshing places, and consequently occasion 
an increased sale of their productions. And 
indeed, I consider that this application of 
the principle will be somewhat important; 
as not only may shops, &c. be thus ren- 
dered, what during hot weather in town, 
will cause them to be much more frequent- 
ed, but also may wines be iced, and creams, 
lemonades, &c. frozen in this manner, be- 
fore the air that does it is allowed to enter 
the room, or shop, so as to render confec- 
tioners, hotels, taverns, &c. &c. independent 
of ice-houses for their supply of ice; and, 
unless I am mistaken, to be also decidedly 
cheaper, than their present method of con- 
gelation. This latter application of the 27 
principle, will also be convenient to private 
life; as both may our wines, beverages, 
creams, &c. &c. be iced by it during sum- 
mer, and our apartments cooled at the 
same time. 
And lastly come, or rather will in time 
come, private houses; which, when expe- 
rience shall have effected the improvements 
it brings about, will, I doubt not (by means 
of companies similar to the water compa- 
nies), in many of the confined parts of Lon- 
don, be, during summer, so ventilated, as 
shall render apartments which are now 
hot as ovens, most gratefully cool and re- 
freshing. 
Such are the advantages we may derive 
from it as preventive of what we suffer from 
the heat of the weather and inefficient ven- 
tilation. 
But these, are by no means the whole of 
the particulars in which I expect we may 
render the principle serviceable—as, unless 
I am altogether wrong, tve may make use 
of it in a way, which, conducing to the pre- 
servation of luxuries of the table, and ne- 
cessaries of life, will render it in some de- 
gree important as a national resource. 28 
By the effect of the air emitted from 
the fountain of Hiero, it is seen that phe- 
nomena, similar to those of an arctic win- 
ter—that is, the instantaneous production 
of both snow and ice, may be produced 
by condensation alone—and it is of course, 
that if this were to be furthered by the air 
in its condensed state, being reduced in 
temperature, as availing ourselves of Les- 
lie's method of producing artificial cold will 
enable our doing, air much below the freez- 
ing point, may be emitted into any place; 
and consequently, that we have the power 
of freezing whatever we choose to expose 
to the action of the so-emitted air. 
Now, by the way in which provisions are 
occasionally kept in countries approximat- 
ing the polar circle (and indeed, in some 
considerably remote from it), we learn, that 
if substances of an animal nature be re- 
duced to below the freezing point, putre- 
faction is so much retarded, as for descrip- 
tions of food which, at other times of the 
year would not keep six days untainted, to 
be perfectly sweet at the end of as many 
months: and, indeed, inferring from the 
length of time bodies are said to keep free 29 
from putrefaction at Spitzbergen, and from 
the state of the supposed antidiluvian re- 
mains found in Northern Asia, it might be 
said, that by a reduction of temperature to 
below 32°, putrefaction, is not simply for a 
period, but for ever prevented.* 
Now, as this is a temperature, which the 
method I have been pointing out, will en- 
able our at all times, both producing and 
maintaining, those of the higher classes 
whose wealth renders it only necessary for 
them to zoill, that this, or the other gratifi- 
cation, shall be administered to their plea- 
sures, ma}r, in addition to having an inva- 
riable temperature maintained in their resi- 
dences, be also enabled to have the pro- 
ductions and delicacies of peculiar seasons, 
all the year round. As, by having arrange- 
ments (a vault, or underground conserva- 
tory, somewhat similar to an ice-house for 
instance, so constructed, as to prevent any 
such admission of heat, as should coun- 
* “ At Spitzburg, the extreme cold will suffer nothing 
to putrefy and corrupt; insomuch, that buried bodies are 
preserved entire for thirty years, and inviolated by any rot- 
tenness. Bartholiuus, de Usu N.ivis, cap. 12.”—Parke’s 
Chemical Essays. 30 
teract the effect) for the purpose of freez- 
ing, and keeping them frozen, those luxu- 
ries of the table, venison, game, salmon, 
oysters, and various other sorts of animal 
food, which are now to be had only at 
peculiar seasons, may be so preserved, as 
to be served up all the year round; it 
being only necessary to immerse whatever 
is thus kept, in cold spring water some 
hours before it is dressed, that it may be 
gently (though it must be thoroughly) 
thawed, and it may be brought to table 
unaltered in point of flavour.* 
And, on the supposition, that the en- 
gine and apparatus, employed to keep any 
public place of a constantly pleasant tem- 
perature, were, when not wanted for that 
purpose, to be made use of—in freezing the 
* “ The Hon. Mr. Boyle relates, that the physician to 
the Emperor of Russia, assured him, that he had had the 
venison of elks sent him unsalted, and yet untainted, out of 
Siberia, which is some hundreds of leagues distant from 
Moscow; and that beef, and other flesh, well frozen, would 
keep for a very long time uninjured; and that it will have 
lost none of its natural flavour, provided it be very gradu- 
ally and thoroughly thawed, before it be dressed for the ta- 
ble. Experiments on Cold, Quarto, London. 1683. p. 
85.”—Parke’s Chemical Essays. 31 
descriptions of food I have been pointing 
out—in icing creams—producing (which 
could most rapidly and cheaply be done) 
common ice for sale, &c. I doubt not, but 
that some of those purveyors of luxuries of 
the table, with which large places abound, 
would be willing to give so much for the 
frigorific use of it, as would repay all ex- 
penses of erection, if not render it a source 
of profit. 
So far, as to rendering the principle avail- 
able to the preservation and production of 
luxuries of the table. As to producing si- 
milar effects with reference to the neces- 
saries of life, it is to be observed, that the 
superiority as to flavour and tenderness, 
which butchers' meat, that has been killed 
ten days or a fortnight, possesses over that 
which is eaten a day or two after killing, is 
so well known, that if it could be done, it 
would be always kept this time, or longer, 
before it is eaten. 
During the greater part of the year, 
however, the state of the weather prevents 
this being done, owing to putrefaction com- 
mencing within that period. But by all 
places in which the method of ventilating that I have been describing is applied to 
the courts of justice, the benefit of having 
butchers" meat kept as long as is desirable, 
before it is eaten, may be possessed ; as, by 
emitting the air which has been employed 
to keep the more costly descriptions of ani- 
mal food from putrefaction, to ice creams, 
See. or to make ice, from the vault in which 
these effects would be produced, into a 
building which should serve as a public 
shambles,it would be kept so cold, as would 
both preserve meat much longer than it is 
now kept, and prevent its ever being fly- 
blown,* See. 
But it is not with reference to the species 
of food which falls under the description 
of butchers" meat, that I primarily referred, 
when speaking of the “ necessaries"’ of life; 
* In places where, as in Leadenhall, and the other flesh- 
markets of London, there are constantly immense quantities 
of animal food exposed to the putrefactive influence of 
summer weather, advantageous application of the principle 
might doubtless be made. As, owing to the possibility of 
keeping the whole of the meat there exposed, in an atmo- 
sphere of whatever temperature might be found best, its 
flavour would be so much improved, and putrefaction so 
set at defiance, as would, L expect, in the long run, amply 
repay the expense. as, by applying the principle to the preser- 
vation of another species of animal susten- 
ance, benefits, decidedly national, may I 
expect be derived. 
If the observation, that “ he who makes 
two blades of grass grow in the room of 
one, does most for his country," indicated 
the insight into the principles of public 
prosperity,it has beenheld to do, it follows, 
that the effecting any thing tantamount to 
this, whether with reference to vegetable or 
animal food, is doing a public service; and 
it will not I apprehend, need proving, that 
had individual perception and exertions, 
instead of the observation and ingenuity of 
generations, possessed mankind of the me- 
thods, by which the vast quantities of ani- 
mal food annually drawn from the ocean 
are obtained, he would have been held up, 
as one of the greatest benefactors of the hu- 
man race. Since, as there is no way,in which 
the same quantity of sustenance, can, in so 
short a time, and at so little expense be 
procured, as by the herring, pilchard, cod, 
mackerel, See, fisheries; and as there is no 
species of food which can be sold so cheap as those fish, during the season for them, it 
follows, that the ability of taking them to 
the extent which annually recurs, is equi- 
valent to the power of raising two blades 
for one, over a very considerable surface of 
cultivation. 
Now, though (as an insular people) we 
possess this power in a degree, superior to 
that of any of our neighbours, it is well 
known that we exercise it to a less extent; 
and much has been said to rouse us to a 
sense of our true interests on the subject, 
and to urge us to exertions similar to those 
of the French and Dutch. But, in treating 
on the subject, the advocates for increased 
exertions, and a more national interest as 
to our fisheries, have overlooked a circum- 
stance, which (so far as relates to home 
consumption) most materially contributes 
to the indifference we manifest, towards 
what, as a maritime people, we ought prin- 
cipally to foster and encourage; that is, 
they have not taken into consideration the 
effect, that results from the state, in which 
the food so obtained, must be eaten. Had 
we been possessed of means of keeping fish, other than by salting, or drying them, I 
doubt not, but that our fisheries would have 
had very much more attention, than they 
have yet received. But, with no other 
means of keeping what are not wanted for 
present use, than by preservation in salt, 
and drying—under the loss of original fla- 
vour which these methods occasion—with 
the superinduction of one less palatable— 
the thirst consequent on eating food highly 
salted—and the facility, with which even 
the lowest among us procure fresh beef, 
mutton, &c.—with these circumstances ta- 
ken into the consideration, our indifference 
to the additional food we might derive from 
the vast pasture-grounds of the deep, is 
accounted for. 
Were our lower classes like those of some 
other countries, so restricted to vegetable 
diet, as for fish to be an invigorating as well 
as palatable change, then would they, in 
whatever way cured, be relished by them. 
But, accustomed as they are to animal food, 
both (excepting when fish are fresh) more 
agreeable to the palate, and at all times 
more strengthening to the frame, there will 36 
never (on the equality between our means 
of production and our population which 
at present exists) arise any greatly increas- 
ed demand for the food we procure from 
the ocean, unless we can contrive so to 
keep it, as both preserving its original fla- 
vour, and doing away with the thirst and 
vulgar infirmity (vide Sir Toby Belch— 
Twelfth Night, act 1, scene 8,) it occa- 
sions, shall increase its consumption in the 
higher and middling classes of society, when 
the lower classes, would doubtless follow the 
“ fashion” to a degree, which might, per- 
haps, give rise to that cultivation of our 
watery patrimony, which has been so long, 
and so justly, advocated. 
Now, though I cannot take on me to 
say that it is certainly in my power to 
point out a method of so keeping fish, as 
shall combine these desiderata, of preserv- 
ing their original flavour, and preventing 
all liability to thirst, or vulgar infirmity, 
from eating them, yet do I conceive my- 
self abundantly authorized to state, that I 
think it is in my power to do this. As, if 
a temperature of about 32° will perm a- 37 
nently prevent putrefaction, and if it is in 
our power to produce and maintain that 
temperature (one of which is well known,* 
and the other I trust, abundantly shewn 
to be the case), it would follow, that pro- 
duce, and keep constantly up this tempe- 
rature, and you bring about these effects to 
whatever extent you please. Shew, there- 
fore, the advantage that might be derived 
from thus doing, to be so much greater 
than the expense of it as would leave a 
handsome profit, and it becomes matter 
of course, that the preserving jish in this 
way would be undertaken, and that some 
of the advantages, which the advocates for 
an increased attention to our fisheries point 
out, would be derived from it. 
As, however, to demonstrate this incon- 
trovertibly, would require an extent and 
accuracy of data I do not yet possess, I 
must content myself with merely shewing 
it, certainly possible, and probably advan- 
tageously practicable. 
# Particularly by the denizens of Billingsgate: since, while 
the ice, in which the salmon they receive from the north 
are packed, remains undissolved, the fish keep sweet, and 
good; but, as soon as it is all thawed, putrefaction begins. 38 
The doing this divides itself into two 
considerations—how can the fish be kept, 
and how could they be advantageous!} 7 dis- 
posed of? 
To the first of these is to be replied—lf, 
into an underground conservatory (vault, 
that is, well insulated, See. so as to prevent 
the admission of heat) of such dimensions 
(100 feet long, SO wide, and 15 deep) as 
would give a capacity of 45,000 cubic feet, 
air were injected at the rate of 500 gallons 
per minute, the whole atmosphere of the 
place would be renewed every nine hours, 
or say (a day's work being only ten hours) 
once a day; and to inject this quantity, 
reduced to the temperature of, say zero, 
would require an engine of five, though, to 
be on the safe side, we'll say ten horses' 
power. Now, an engine of that power, 
with the apparatus necessary for operating 
on the air, I am perfectly satisfied would 
not cost so much as 5000/. As, however, 
there is, with reference to. the apparatus 
uncertainty, to be on the right side in this 
particular also, I will suppose engine, and 
apparatus, as costing 10,000/.; and as the 
fuel (a bushel of coals being capable of producing an effect, equal to the labour of 
ten horses for an hour) and attendance the 
engine and apparatus would require (sup- 
posing the engine to be working ten hours 
a day, for six days of the week), would come 
to (fuel, 4/. 10s.; the engineer’s and his la- 
bourer’s wages, 3/. Os.—"11. 10s. ; though, 
to be still on the safe side, I’ll say) 10/. per 
week, here is capital embarked, and ex- 
pense incurred, to an amount of 1020/. a 
year, exclusive of the rent of, or per cent- 
age on, the cost of the vault, which I will 
consider as 80/. per annum more, making 
an aggregate of 1100/. annual expenditure; 
which aggregate, I will again increase by 
400/. on account of the labour of hanging 
O 
the fish up, clerk’s salary, See. We thus 
incur an expenditure of 1500/. per annum, 
to effect the purpose of injecting per diem, 
300,000 gallons of air at the temperature 
of o°, into a place, in which it is intended 
that fish shall be suspended, for the purpose 
of being, if not frozen, yet reduced to a 
temperature so near the freezing point, as, 
preventing putrefaction, would keep them 
as long as we pleased. 40 
The next question is. On how many fish 
will the capacity of the place thus treated, 
enable our producing this effect ? 
Prior, however, to replying to this, it 
must be observed, that as I consider mac- 
kerel and herrings (and in some places sal- 
mon, oysters, and scollops) the only fish, 
with reference to which it would be greatly 
advantageous to make these arrangements, 
I shall confine my observations to them. 
And of the first—mackerel, as it would 
be possible to suspend ten of them in a 
cubic foot, 450,000 is the number on which 
this preservative effect might be produced. 
Having thus the amount of effect produced, 
the consideration next becomes, What would 
these fish cost, and what could they be sold 
for? 
An offer of threepence each, or thirty- 
three shillings per hundred (fisherman's 
tale) for mackerel, is I believe, a price for 
which, whatever number was wished for, 
could be got gutted, cleaned, and ready 
for suspension. 
And at this price, 450,000 would come 
to 56251. 41 
Now, if I bear at all correctly in mind the 
selling price of mackerel in London,sixpence 
apiece, is what might certainly be got for 
them there, if sent to market at such a pe- 
riod after the mackerel season had ceased, 
as would admit of the public palate's reco- 
vering from the satiety, which the abund- 
ance of a plentiful season, may be supposed 
to create. 
If, therefore, they were kept till then, 
and then sold at that price, 4125/. is the 
amount of profit that would be made by 
them, supposing them to be sold no where 
but in London, and at only sixpence each; 
to neither of which, do I expect, the course 
of sale would be restricted. Since, as (there 
being in mackerel, on an average, a pound 
and a half of good, firm food) they would 
at this price, be decidedly cheaper than 
butcher's meat, and also, as the great quan- 
tity of ice, the apparatus would (without 
any increase of expense*) produce, would 
# Among the particulars Mr. Fisher details, relative to 
the Polar Expedition, he states, that on the 15th of Februa- 
ry, 1820, when the thermometer stood at 50 below zero, 
w'ater, dropped from the main-top, (a distance of 40 feet 8 42 
enable our doing by them, as is done by 
salmon—i. e. packing them up in ice, so as 
for them to be sent inland, to places where 
they are now never tasted, I see no reason 
to suppose, but that the demand for them, 
would be increased to an extent, which 
would cause them to fetch more than six- 
pence each. 
But this is not the whole of the advantage 
that might be derived. In the estimate of 
inches,) was frozen into spheroidal pieces of ice, before it 
reached the roofing of the deck. Now, as the rate at which 
water gains, or loses heat, is proportioned to the surface it 
exposes, to the communicating, or abstracting medium* and 
as there is no way of causing it to expose so much surface, 
as by following the principle on which icicles are formed, 
i. e. percolating it upon a vertical solid, so as for it to be 
circumfused as thinly around that solid, as its gravitating 
principle will admit—as there is no way of abstracting ca- 
loric from, and consequently freezing water, equal to this, 
by treating it thus, in the pipe, or aperture, by which the 
freezing air passed off from the vault, ice might, unless I 
am altogether mistaken, be produced in greater quantity, 
than we could ever have occasion for it; and at an expense, 
less than that of procuring it, as got for ice-houses, in the 
proportion of the difference, between suffering the waste 
water of the engine to run to be frozen, and the labour at- 
tending the transporting natural ice, from where it is pro- 
cured, to where it is kept; and this, independent of the ex- 
pense of packing it, and then getting it up again for use. expense, it will be seen that I have includ- 
ed the disbursements of the whole year. 
But instead of the probabilities being, that 
the fish thus preserved, would require the 
whole year to be disposed of, they are so 
much the other way, as that it is to be ex- 
pected, the fish would be all sold before the 
herring season came in; and if so, there 
might be a second per centage made upon 
the capital embarked. 
Since as, on the supposition that the 
place was cleared of mackerel, by the 
time the herring season came in, herrings 
could be kept in the same way—as the num- 
ber that could thus be kept (allowing thirty 
to a cubic foot) would be 1,350,000—as they 
could be got at the rate of a farthing each, 
or two shillings and ninepence per hun- 
dred (taker's tale)—and as they could doubt- 
less be sold again at three farthings each, 
or eight shillings and threepence per hun- 
dred (which would render them only about 
half the price of butcher's meat), 2812/. is 
what would be made by the transaction; 
which, added to what was before gained, 
gives a profit (calling the capital embark- 
ed 20,000/.) of above 34 per cent, a re- 44 
turn, which would be ample inducement 
to capitalists, so to embark in it, as would 
at once render the thus preserving pisca- 
tory food a national object, provided the 
data on which I have calculated are correct, 
and that the flavour of the fish should be 
uninjured, by thus keeping them.*. 
It will be observed, that I have gone only 
roundly into the subject, and that minor 
considerations, such as the expense of trans- 
porting the fish from where they would be 
taken to Town, the exact amount of capital 
required, &c. See. are not touched on. The 
reason of this, will at once be seen to arise, 
from its being unnecessary to dwell on mi- 
nutia of this nature, provided a generally 
correct result is given; and that what is 
* And that nothing of this kind would take place, may at 
once be seen, by all who partake of salmon in London. 
Since, as those fish have all been kept from putrefaction, 
during their transportation, from those parts of Scotland, 
and the north of England, where they are taken, to Town, 
by being sent, packed up in pounded ice, and consequent- 
ly kept at a temperature of about 32° j and as they keep 
sweet, a longer or shorter period (a fortnight—three weeks 
—or month) according as the quantity of ice put around 
them, remaining undissolved, prevents their becoming of a 
higher temperature, here is proof, that no deterioration in 
point of flavour, would arise from what I propose. 45 
passed over on the debit, is, (as is now the 
case,) decidedly less, than what is omitted 
on the credit account; particularly, when 
the other uses and advantages, which it is 
evident, might be made of apparatus capa- 
ble of producing ices, &c. are considered. 
The circumstance, of course, applies to 
salmon, oysters, scollops, and, indeed, to 
all fish that are taken at particular seasons 
only ; profits on which might be made, as 
circumstances rendered them more or less, 
articles of luxury. 
These are the advantages, I expect we 
may derive from it, as applicable to public 
convenience and benefit. But these, though 
considerable, are by no means the whole 
of the particulars in which we may render 
the principle available to our service; as by 
a somewhat more operose method of proce- 
dure, it may, I think, be made to produce 
effects, important perhaps to scientific re- 
search. 
The difference between our capabilities 
as to the production of temperatures above, 
and below the zero of Fahrenheit, and that 
our range on the ascending, is many thou- 46 
sand times greater than that on the de- 
scending scale, is well known. 
Now, by operating with a succession of 
apparatus, and increasing effect by a com- 
bination of influences, our range on the de- 
scending scale, may, I expect, be increased 
to an extent, which, if it will not actually 
decide whether the zero of calculation, is 
that of fact, will, at least, enable our pro- 
ducing temperatures very much below 
any that have yet been obtained, and ap- 
proximate us, perhaps, as closely to the 
real zero, as it will ever be possible to attain. 
Since, if the condensation of the air operat- 
ed upon, were to be increased as we have 
it in our power to increase it—if, when thus 
condensed, the vessel in which it was, were 
surrounded with one of the most intense of 
the freezing mixtures—and if the air, when 
thus cooled, were to be emitted upon, and 
around, another condenser, in which other 
air was compressed to the same degree—by 
carrying this method of operation home, 
the air emitted from the last condenser of 
the series, would, I expect, be as near the 
real zero as we shall ever be able to attain; 47 
and perhaps, both enable our reducing 
those of the gases, which have yet been ob- 
tained only in the gaseous, to the fluid, or 
concrete state, and (it may be) open a new 
door, of chemical investigation. 
But neither is this the last of the particu- 
lars, in which I expect we may render the 
principle serviceable at home; there being 
yet to be noticed, one, which, though not so 
widely beneficial as these may be, is per- 
haps, more vitally important. 
We all know, that our national complaint 
consumption, intermits with the weather, 
and that the unfortunate subjects of it suf- 
fer more or less, and are carried off, more or 
less rapidly, as that is mild or severe. Now, 
if a chemical change does not take place as 
to the constitution of the atmosphere, in 
winter and in summer—and that there does, 
no one has yet, I believe, found reason to 
suppose ; and if all the difference between 
the summer and winter states of it, is that 
produced by its being of a lower tempera- 
ture, and more charged with vapour in one 
than in the other—and that this is the only 
difference, would (independent of chemical 48 
analyses) appear from the relief experienced 
by asthmatic, and consumptive subjects, 
on entering a warm, dry room, after being 
exposed to a cold, damp air—if this is all 
the difference there is, betiveen the summer 
and winter states of the atmosphere, it is 
most certainly in our power, very much to 
relieve, and, I would hope, considerably to 
prolong the lives, of all who suffer under 
asthmas and consumptions among us: since, 
all that under this supposition, it would be 
necessary to do, is to supply some building,* 
in which those, who suffer under these af- 
flictions, should, during winter reside, with 
an atmosphere constantly, (both night and 
day,) mild and dry—that is,of whatever tem- 
perature might be desired, and freed (arti- 
ficially) from the damp vapours, with which 
it is, during winter, so frequently charged ; 
and as, from the latter's being equally prac- 
ticable as the former, this is what may be 
* A kind of immense hotel, for instance, with a public 
room, of such length and width, as would be sufficient for 
ample exercise ; and in which, though all who were in it 
would partake of the benefit it was built to afford, yet might 
any one, have single, or suites of apartments, to themselves. 49 
done; it may be presumed, that many of 
those, whose only relief at present, is flight 
from our winter, to those of the south of 
France or Italy, may be benefitted to an 
extent, which only themselves can justly 
appreciate. 
That in saying this, I shall be charged 
with the common fault of speculatists, car- 
rying theory farther than practice can fol- 
low, I am well aware. But, if I see the case 
aright, this is a charge, which I shall be able 
to refute. Since, as it has only two features, 
those of attainment in point of practicabi- 
lity, and of expense; and as, unless I de- 
ceive myself, the peculiar circumstances of 
the affliction, render the latter, not more 
difficult than I trust to be able to shew 
the former, theory, will not in this instance 
go farther than practice, strange as it may 
appear, to talk of rendering the air as dry 
in the dampest and rawest days of winter, 
as it is in the driest and finest of summer. 
Since, as by the effect of the emission of 
air, from the air-vessel of the fountain of 
Hiero, we learn, that if it be reduced to a 
certain temperature, under a certain de- 50 
gree of compression, and then allowed to 
expand to the atmospheric pressure, the 
aqueous vapour it holds in solution, is in- 
stantaneously congealed, and precipitated, 
all that we should have to do to render air 
dry as we please, would be, first, to condense 
and cool it to below 32, that on liberation 
from the condensation, the vapour it held, 
might be frozen, and consequently precipi- 
tated, and separated from it, and then, to 
raise its temperature to whatever should be 
pleasant, and inject it into the place in 
which those, whom it is intended to relieve, 
were; when, owing to the dry state, to which 
the joint effects of the precipitation of its 
vapour, and the subsequent heating would 
bring it, it would enter the place, drier per- 
haps, than the air of any of the finest days 
of summer. 
Having thus illustrated the attainment 
of what I propose, so far as practicability 
is concerned* I turn to the other feature of 
the consideration—its attainment in point 
of expense; and on this it is to be remark- 
ed, that though it would undoubtedly be 
considerable, yet, as the benefit would 51 
also be great, and as by operating on the 
principles of pneumatic medicine, and avail- 
ing ourselves of the (in this particular) soft- 
ening effects of carbonic acid gas, we may 
possibly produce factitious atmospheres, 
soft as those of the mildest climates: in 
consequence of these capabilities, and of 
the wealth of many of those, who would be 
desirous of the relief I point out, I look up- 
on what I suggest, though not as a thing of 
very easy attainment, yet as what is by no 
means impracticable. 
That there is scarcely one in ten thou- 
sand, but what thinks otherwise, I am fully 
prepared to find. But, as owing to there 
being fewer than one in ten thousand, aware 
of the capabilities we possess, the impedi- 
ment will, in the eyes of the many be, not 
whether, but how it can be done; and as ow- 
ing to the scale on which Leslie’s method of 
producing intense cold can be applied, it is 
indubitably in our power to cool the air in 
its condensed state, to whatever we please, 
and consequently to render the precipita- 
tion of its vapour certain : and also, as pro- 
vided the principle is but applicable, the advanced state of chemical science, and our 
manufacturing and mechanical means, will 
soon surmount the mere difficulties of appli- 
cation, insurmountable as they may appear, 
I am content to bear the charge of advo- 
cating, a medical Utopia. 
These, are the advantages I consider we 
may ourselves, and at home, derive from it. 
But great as these advantages are, yet 
can I not but hope that they maybe placed 
lower in the scale of estimation than others 
yet to be enumerated. 
Since, if the view I take of the subject 
is correct, and what I propose as to reduc- 
tion of temperature practicable to the ex- 
tent I consider it, it is not in the light of 
an addition to the conveniences and luxu- 
ries of man only* that the subject is to be 
viewed, but as a mean by which,it is possible, 
the ranges of those dreaded scourges, the 
plague, and yellow fever, may be circum- 
scribed. 
The circumstances which cause me to 
hazard this observation, are these. From 
the effects, which warm weather produces 
as to the spread, and cold weather as to 53 
the prevention, of the plague* and yellow 
fever, it may be inferred, that to their pro- 
pagation, an atmosphere of somewhat ele- 
vated temperature, is absolutely necessary ; 
and that against their propagation, an at- 
mosphere of very low temperature, is a po- 
sitive preventative. Now, if so, it may be 
expected, that the method of cooling air 
which has been described, places in our 
hands, the power of circumscribing these 
depopulating scourges. Since, operate as 
I propose, and any building, even under 
the line, may be supplied with an atmo- 
sphere low as that of the frigid zones; and 
supposing this to be done with reference to 
a hospital, for plague, or yellow fever sub- 
jects, and that it were constantly kept at a 
temperature, considerably below the freezing 
point, might not the contagious influence 
be, if not destroyed, yet so neutralized, as 
would free those who attended the infect- 
* “ If all this be true, there is the less reason to pre- 
sume that the plague was the product of the atmosphere in 
that year; since cold is generally admitted, to be, not 
only adverse to its production, but incompatible with its 
existence.”—Sir A. B. Faulkener, M. D. in his late Trea- 
tise on the Plague. Ed from any risk, except that arising from 
actual contact; and if this should prove to 
be the case, would not the ranges of those 
awful visitations, be brought almost within 
our control ? 
This is the principal advantage, which I 
am willing to hope may’ be derived from 
what I propose; and although its magni- 
tude, and the extent to which it would be 
a blessing, are too great to admit of its be- 
ing lightly presumed on, yet, as it is amply 
within the verge of possibility—as it is not, 
abstractedly considered, more remote from 
expectation than other capabilities of which 
philosophy has possessed mankind—and as 
indulging the anticipation cannot be inju- 
rious, and may lead to investigations pro- 
ductive of general benefit,* I shall yield to 
the pleasing idea, of what are the advan- 
tages which might be derived from it, sup- 
posing it to have the effect I suggest. 
* A friend of mine, who is a Spanish merchant, has 
informed me, that one of the clerks of his house of busi- 
ness at Cadiz, when given over, on an attack of yellow fe- 
ver, and deemed so beyond remedy, as for the physician 
to have desired them to order his coffin, was recovered, and 
restored to health, by being rubbed over with, and, as it 
were, bathed in, pounded icc. And taking them as they appear to stand 
in the scale of precedence, the application 
of the principle at Gibraltar and Malta, may 
perhaps be deemed the principal advan- 
tage we should ourselves derive from it, 
would it have the effect I have been sng> 
gesting ? As then, the establishment of hos- 
pitals on the principle there, would possess 
the garrisons of means of counteracting 
those constantly dreaded scourges the 
plague and yellow fever, which could only 
be sufficiently appreciated, were some of 
those circumstances which occasionally 
frustrate the most judicious preventive re- 
gulations, to introduce the infections among 
them. 
Sierra Leone, is that of our own posses- 
sions which would rank next to Gibraltar 
and Malta; owing, not to the plague, or yel- 
low fever, but to the losses the colony an- 
nually experiences from the insalubrity of 
the rainy season; and though it is not sup- 
posed that climate could be so counteract- 
ed as altogether to prevent this, yet do I 
trust that it could mainly be counteracted. 
Since, as in addition to supplying any 
hospital which should be erected on the 56 
principle, with a cool medium jof respira- 
tion ,it is (as I have shewn with reference 
to a dr/ atmosphere for consumptive and 
asthmatic subjects) also possible to render 
the air which should be injected, dry as 
that of our climate in fine weather ; so that 
instead of having as they now have, the fe- 
ver of the country heightened by the hot, 
humid, steam-like atmosphere of the rainy 
season, invalids might then constantly be 
in, and respire, an atmosphere always dry, 
and of a pleasant temperature; and as this 
is what it might be expected, would most 
materially tend to counteract the diseases 
the rainy season gives birth to, there is per- 
haps no other of our colonies where a pro- 
vision of this nature would be more a bless- 
ing, than it would there. 
To those also of our foreign possessions, 
whose importance renders it necessary they 
should be garrisoned, notwithstanding in- 
salubrity of climate or situation; to such, 
the principle might be applied with most 
beneficial effect as to the health of the 
troops; as, by having a building large enough 
to allow them to take constant in-door ex- 
ercise, in the dry, temperate, and salu- 57 
brious atmosphere, any place might be 
supplied with, their health and spirits (sup- 
posing them to have to endure the confine- 
ment of a long rainy season) would be so 
kept up, by the recreative exercises which 
would be resorted to for amusement’s sake, 
as would materially counteract the climate, 
and, it might be expected, much decrease 
the mortality of Europeans. 
Such are the advantages we may nation- 
ally derive from it. 
Those, which others may derive, vary with 
their situations : and the parellel of latitude 
may be considered as a general ratio of ap- 
preciation ; the higher latitudes having less, 
and the lower, greater occasion for it than 
ourselves. 
And looking at it thus, it might be ex- 
pected to come into general use in all 
places within, or near the tropics,* where 
the expense of it could be afforded. 
* The south, or rather the whole, of France,—Spain,— 
Portugal,—ltaly,—the coasts and islands of the Mediterra- 
nean, Adriatic, &c.—our East Indian empire, and the south 
of Asia in general:—wherever in Africa they are sufficient- 
ly civilized ;—the West Indies, and portions of both North 
and South America, Sac. Sac. Sac. 58 
Since, though this expense would be 
great, yet as effeminacy and desire of ease, 
are the characteristics of hot climates, and 
as nothing would there be so great a luxury, 
as the temperatures which the method I 
propose would enable them to command, 
it would not perhaps be too much to say 
that even poverty would tax itself, to pro- 
cure the relief and gratification which could 
thus be given; particularly when it is con- 
sidered, how abundantly it will both supply 
them with ices, and enable their beverages 
being cooled as they please.* 
* “In this Island, the use of ice at table is considered as 
a mere luxury; but, in the hot climates, it is viewed in a 
very different light—as an indispensable necessary of life, 
and highly grateful and salubrious. The ancients were ac- 
customed to cool their liquors during summer, by mixing with 
them pure snow, carried down on purpose from the moun- 
tains. But, about the middle of the fifteenth century, the 
method was discovered in Italy, of freezing water, by applica- 
tion of the superior cold, produced from the mixture of 
snow, with salt, or nitre. In the East Indies, great expense 
and attention are bestowed, in procuring the refreshment of 
cool drinks. On the coast of Malabar, the air is generally 
too humid for producing any considerable effect by evapo- 
ration ; but, in the interior of the province of Bengal, during 
the continuance of the dry season, when a piercing wind gene- 59 
But of all settlements and possessions in 
rally blows from the lofty mountains of Thibet, films of ice, 
about the thickness of a shilling, or half-a-crown, are gathered 
in the mornings, from the surface of shallow earthen pans, set 
close to the ground, in pits, lined with the bamboo reed, and 
which have been filled the preceding evening, with water pre- 
viously boiled, and again suffered to cool. These thin 
sheets of ice, are immediately rammed together into a com- 
pact mass, and sent down, packed in wool, to Calcutta. 
But, during at least four months of the year, this resource 
totally fails, and the settlers, deprived of their usual indul- 
gence, then suffer from excessive languor. 
“In the West Indies, again, and the adjacent shores of 
America, our colonists are, at all times, left without such re- 
lief, to assuage the burning heats of a pestilential climate. 
Even at home, ice-houses often fail in their construction, 
and are seldom found to answer, in the southern and west- 
ern districts, such as Devonshire and Cornwall. To pro- 
cure ice, therefore, independent altogether of the disposition 
of the sky, is a benefit of no small importance. A minute 
fragment of ice will yet be sufficient, in melting, to chill 
a very large body of water. But the cold affusion, has 
been employed with the happiest success, at certain stages 
of fever. Cooling draughts may, in many cases too, be ad- 
ministered with obvious advantage j and though medical 
writers are not always consistent, either with themselves or 
with nature, the uniform belief and experience of whole 
nations, sufficiently establish the utility of the application 
of cold, both externally and internally, in a wide variety of 
disorders which assail the human frame.” 
Leslie'—Relations, &c. the other continents, Batavia, that “ grave 
of Europeans/" is the place which (with the 
exception of America, should it operate 
with reference to the yellow fever as I have 
suggested) might perhaps derive most ex- 
tensive benefit, from the adoption of the 
plan; owing to the superiority of its Eu- 
ropean population, to any settlement, on an 
equally insalubrious spot; and the conse- 
quent greater importance of that applica- 
tion of it, which should supply them with 
cool and dry atmospheres, notwithstanding 
the exhalations, the excessive heat raises 
from their stagnant canals. 
And as to the only objection there can 
be, to the thus counteracting climate— 
the expense—where is he among us, who, 
knowing the mortality of the rainy season 
at Sierra Leone, would urge this, should 
the effect be what I suggest, and the ex- 
pense no more than I anticipate; that 
is—first, two buildings; one to serve as 
a hospital, and the other (being long, wide, 
and high) as a place of exercise, and invi- 
gorating recreation (walking, bowls, tennis, 
&c. &c.) for the European population of 61 
the settlement during the rainy season; 
secondly, a steam-engine with condensing 
and exhausting pumps, sufficient to ope- 
rate to the necessary extent; thirdly, a 
sufficient series of receivers; and fourth- 
ly, the apparatus which would be ne- 
cessary for precipitating the vapour of, 
and consequently drying, and then warm- 
ing again, the air which is to be injected. 
These things, with the attendance 
and fuel of the engine, and the acid 
for taking up the vapour the vacuum 
would cause, is all the expense it would oc- 
casion ; and as this, when put in competi- 
tion with the object in consideration, is 
(nationally speaking) as nothing, provided 
it does but effect what I suggest, it would 
not, were the effect certain, instead of only 
probable, deserve consideration; though, 
as the whole expense would most likely 
fall short of 20,000/. and as, if effective, the 
colony would be provided with a perma- 
nent means of counteracting the confine- 
ment, steam-like atmosphere, and insalu- 
brity of the rainy season, it would be worth 
the trial even if thrown wholly away. 62 
Such are the benefits, I am willing to ex- 
pect, may be derived from what I propose; 
and as, be what I have hazarded as to the 
prevention of contagion futile as it may, 
neither the application of the principle to 
purposes of ventilation, to the relief of 
consumptive cases, nor to the counteract- 
ing insalubrity of climate are affected, in 
one or the other of these ways, it must, I 
conceive, be made to conduce to the benefit 
of mankind. Since, as the spring and prin- 
ciple of the proposition is power, and as 
power (let me have erred in my estimate, 
and underrated that which would be neces- 
sary, as I may) is what the mechanical 
agencies the world now possesses renders a 
matter of easy attainment, let it but be 
proved, to have either of the effects I have 
been pointing out, and its adoption would 
soon become as much matter of course, as 
any long followed provision, against insa- 
lubrity of situation. 
But the advantages which public assem- 
blages among ourselves might derive from 
this method of ventilation, are greater than 
have yet been noticed; as, by a variation of 63 
apparatus, the means employed, in summer, 
to cool the air to whatever we might wish, 
may, in winter, be made use of to warm it; 
and to supply us, not simply with atmo- 
spheres of whatever temperature we might 
desire, but also, so to supply them, as shall 
both prevent any place ever becoming ei- 
ther hotter or colder than we might wish, 
and do utterly away with, and render to- 
tally impossible, the chilling and danger- 
ous drafts, and currents of cold air, expe- 
rienced by all, who are near the doors or 
windows of crowded places; so that any 
one might sit close to either door or win- 
dow, without ever being annoyed by the 
least draft from them ; and also, would peo- 
ple of delicate constitutions be relieved 
from danger of taking cold, owing to the 
transition from an excessively hot to a cold 
atmosphere, as is now the case when leav- 
ing places of public resort in cold weather. 
That this may be done, will be seen, if 
the principles on which “ drafts'" take 
place are familiarly illustrated. 
There are two principles which operate 
to alter the state of air, in any place where 64 
numbers of people convene. One of them 
affects it physically, and to a change of den- 
sity ; and is the cause of drafts and influxes 
of cold air: the other affects it chemically, 
and to a change of quality, as the medium 
by which the action of the lungs is ren- 
dered efficient to the preservation of life; 
and renders necessary, and indeed indispen- 
sable, the drafts and currents of which the 
first is the cause. The first of these occurs, 
as to any place in which air is heated; the 
other,only in those places, in which it under- 
goes respiration. Now, it is the first only 
of these that falls under our consideration, 
when directed to the principle on which 
drafts take place; and the course of opera- 
tion of this principleis thus. If heat be com- 
municated to a particle of air, a change 
takes place as to that particle in the follow- 
ing manner ; it becomes expanded and in- 
creased in bulk, in some such way as may 
be conceived by reference to the juvenile 
practice,of holding a flaccid bladder before 
the fire, to tighten and fill it up again, prior 
to using it as a football. 
By this expansion it is increased in bulk, but not in weight, and in consequence, 
rises from among the other particles, and 
ascends toward the ceiling; in the same 
way as a bladder filled with air would rise 
through, and swim at the top of others filled 
with water, were they thrown into the sea 
together: and, as the only circumstance 
which caused this particle to be where 
it chanced to be, at the time this supposed 
heating took place, was its gravity, the mo- 
ment that becomes altered, and it, in con- 
sequence rendered specifically lighter than 
the surrounding particles, it ascends, and 
passes through them toward the ceiling. 
This is the course of operation of the prin- 
ciple ; the effect of it is this. As soon as 
this particle of air- has moved away from 
what heated it, its place is taken by an- 
other, which, undergoing the same change, 
passes off in like manner, having its place 
taken by a third particle; and this alter- 
nation continues, all the while heat is thus 
communicated, be the communicator what 
it may, whether the human body, a stove, 
or any other method of heating. 
This is the effect of air's being heated; its 66 
physical state is altered, and it becomes 
specifically, lighter than it was before. 
The consequence of its becoming lighter. 
may be conceived thus. 
If you were to take a 
glass tube, shaped in this 
manner, with a notch or 
crevice cut in it at A, to 
which notch or crevice, a 
metallic slide were well 
and tightly fitted, so as to 
cut occasionally off the 
communication between 
the two legs ; if, into a 
tube such as this, you were 
(when the slide was pushed in, so as to cut 
off the communication) to pour, in one leg 
quicksilver, and in the other water, and 
then, when both were full (placing the 
thumb on the top of the leg that had the 
water in it, so as to keep it in) you were to 
pull out the slide between the quicksilver 
and water, so as to let them press one 
against the other, it is very evident, that 
the superior weight of the column of quick- 
silver, would cause it to press the column 67 
of water upward against the thumb, and 
that, were the thumb removed, the water 
would be driven up, and some of it forced 
out of the tube ; and also, that the water 
would continue to rise, till the contents of 
the two legs counterbalanced each other. 
Now, this is an illustration of what takes 
place as to any building, whenever the air 
inside it, is hotter than the air without. 
Since, as the external air, is then heavier 
than the internal air, the former so ope- 
rates upon the latter, as to press it upward 
against the ceiling, in the same manner as 
the water would be pressed against the 
thumb; and if a part of the ceiling be cut 
away, so as to open a means of emission 
similar to what the removal of the thumb 
permitted; that is, if a ventilation aper- 
ture be opened in the ceiling, the superior 
weight of the cold external air, will cause it 
to drive the lighter internal air, up through 
that aperture, till the equilibrium becomes 
restored; and if, owing to the air on the in- 
side being, by the respiration, &c. of peo- 
ple convened in the building, kept constant- 
ly warmer and lighter than the external 68 
air, this equilibrium is prevented, and the 
difference between the external and inter- 
nal atmosphere, kept permanently up, the 
consequence then will be, that instead of a 
single and transitory emission, like that of 
the water from the tube, there will be a 
continuous emission of air through the 
ventilator, all the while the respiration &c. 
of those who are assembled in the building, 
keeps up the difference. Now this is what 
takes place in all public places ; and, as ow- 
ing to the doors and windows being during 
cold weather, kept shut, the aperture of 
admission (or channel, by which the exter- 
nal air enters the building) is rendered very 
much smaller than that of emission; to 
make up for the difference thus caused be- 
tween the apertures of admission, and emis- 
sion, the cold external air, is as it were, 
obliged to make use of all the cracks and 
crevices that are about, either the doors 
and windows, or elsewhere around the 
building; and to introduce itself through 
them, with a velocity so much greater than 
that at which it passes off by the ventila- 
tor, as will make up for the difference be- 69 
tween the sizes of the cracks and crevices 
by which it enters, and that of the ventila- 
tion aperture. 
This is the reason, why drafts are expe- 
rienced from the crevices of doors and win- 
dows: the heated and respired air passes 
off by the ventilator; to make up for what 
so passes off, fresh air flows into the bot- 
tom of the building; and as, when the wea- 
ther is cold enough to make us shut the 
doors and windows, ingress, by a duct equal 
to that of egress is prevented, to make up 
by the rate at which it enters, for the differ- 
ence in the sizes of the apertures of admis- 
sion, and emission, the air that finds its 
way in through cracks and crevices, enters 
with so great a velocity, as to cause the 
chilling currents we experience. 
It will be as well to remark here, that if 
this is the cause of drafts and currents 
through cracks and crevices, it may be ob- 
served by some one, that all that it would 
be necessary to do to prevent them, would 
be to have somewhere in the building an 
aperture of sufficient size to Jet air in, as 
fast as it passed off by the ventilator; as 70 
then, the necessity for its entering by cracks 
and crevices being prevented, it would ei- 
ther not come in at all through them, or 
with so diminished a velocity, as would pre- 
vent its annoying as it now does, those 
who are near them. This observation may 
very justly be made. But although the 
effect would certainly be according to it, 
yet would there be attending it the disad- 
vantage, of the remedy’s being worse than 
the disease. Since, as the air that entered 
through this aperture would be cold exter- 
nal air, its admission would be attended 
with so chilling an effect, as would render 
it necessary instantly to close the aperture, 
and to submit to the old inconvenience of 
drafts. But, as the first principle of the 
method by which I prevent drafts, is by 
injecting, not cold air, but air raised to 
whatever temperature the coldness of the 
weather may render desirable, the inconve- 
nience I have been shewing is completely 
obviated; as will be seen by giving the 
course I follow. 
Instead of suffering ventilation to take 
place at, as it were, the pleasure of the air, 71 
I restrict and regulate it thus. I first have 
the windows of the place nailed down, so as 
to prevent them from being ever opened : 
I then have the joints and crevices, both of 
these windows and of the room in general, 
so filled with putty, or so treated with any 
such kind of lute, or luting, as will answer 
the purpose, as shall prevent their becoming 
channels, through which drafts or currents 
may find their way either into, or out of the 
place. I then have the door-ways arrang- 
ed thus. Removing the present doors, I 
make the door-way six feet wide by about 
the same height, and have fitted, and (by 
puttying, luting, &c. &c.) made air-tight 
into it, a cylinder (of wood or metal) closed 
at both ends, and placed upright on one 
of them, so as to appear somewhat like a 
cask built into the wall. Through the side 
of this cylinder I have two apertures cut. 
each about four feet wide by the height of 
the cylinder inside its ends; which apertures 
are opposite; the middle of each, being 
in the line of the centre of the cylinder, so 
as to leave a way of about four feet wide, 
right through the middle of it into the 72 
place, as shewn beneath, where the cylinder 
is represented as placed in the wall, with 
the apertures in it. In the centre of the 
cylinder, I have now put (perpendicularly) 
a shaft, of about three inches diameter, and 
of the length of the cylinder; and having 
it, and the centres of the top and bottom of 
the cylinder, so prepared and fitted to each 
other, as that the shaft may easily turn 
round or revolve, I then have fixed on it, 
at right angles to each other, and four at 
top, and four at bottom, eight arms, or 
radii; the bottom four, being exactly under 
the upper ones. To these arms, I have 73 
fixed four sheets, or pieces of iron plate, of 
such lengths and widths, as will just go 
into, and fill up (though without touching) 
the space, left between the shaft, and the 
side of the cylinder; and these things being 
so done, as that the plates or leaves fixed on 
the arms, may turn easily round inside the 
cylinder; and the inside the cylinder, and 
the ends and sides of these leaves, being so 
fitted to each other, as that, when the 
leaves are turned round, there may not be 
a space, greater than about the sixteenth of 
an inch, left between them, the arrange- 
ments for the door-way are complete; and 
the cylinder, through which the place is en- 
tered, has within it, four leaves, or wings, 
somewhat like the fans of a winnowing ma- 
chine, fixed perpendicularly. 
Now the effect of these arrangements, is 
this. Were a common door to be made use 
of, whenever it was opened, free egress, or 
ingress, would be given to air, and it would 
pass from, or into the place, as circum- 
stances dictated. But with a door, arrang- 
ed as I have described, no air can, at any 
time, pass either into, or out of the place, 74 
excepting, by the narrow space, or crevice, 
left between the edges of the leaves, and the 
inside the cylinder ; since, as the leaves are 
all at right angles with each other, and as 
the two apertures in the cylinder are nei- 
ther of them so wide, as to be equal to nine- 
ty degrees of a circle of the same diameter 
as this door-way cylinder, it follows, that 
turn, or cause the leaves to revolve as we 
may, two of them will always be within the 
uncut parts of the cylinder, and constantly 
interposed, between the inside the place, 
and the open air; and, in consequence, 
there never can be any other passage for air, 
into, or out of the place, by this door-way, 
than by the space or crevice, between the 
edges of the leaves, and the inside the cy- 
linder. 
When the windows and door are thus 
finished, I proceed as follows with the ven- 
tilator. To the aperture in the ceiling, 
through which ventilation takes place, I 
have fixed a pipe of the same diameter as 
that aperture; which pipe, goes through 
the roof, and then descends, and opens in- 
to a reservoir, or cistern, as represented 75 
beneath, where the dotted line shews the 
pipe inside, and the continued line shews it 
outside the roof. 
Now, with things thus arranged, and with 
the cistern so far filled with water, as im- 
merses the end of the ventilation pipe a few 
inches in the water, I set the machinery, by 
which the warmed air is injected at work; 
when air, fresh, and of a temperature plea- 
sant to the feelings, is injected at such a 
rate, as is sufficient for the consumption of 
the people inside; and as from the arrange- ments, and lutings I have mentioned, the 
only places were this air can find egress, 
are, through the ventilation pipe, and by 
the spaces or crevices, between the door- 
way cylinder, and the leaves that revolve 
in it; and as these spaces or crevices, are, 
when the cylinder and leaves are well 
finished and fitted to each other, as almost 
nothing, in comparison with the quantity 
of air injected, it follows, that the ventila- 
tion pipe must be the main channel of 
exit; and also, as before any air can pass 
through this pipe, it must displace the wa- 
ter inside that end of it which is immersed 
in the cistern; as, to displace this, a slight 
pressure must be thrown upon it; as the 
causing this pressure, will somewhat (most 
trivially to be sure) condense the air in the 
ventilation pipe; and also, as this conden- 
sation, will, owing to that principle of fluids, 
by which action and reaction are commu- 
nicated, be reverted,or reflected back upon, 
and caused to take place with respect to, 
all the air in the place, the whole of it will 
be somewhat condensed, and, in conse- 
(juence, the place will have in it a quantity 77 
of air, greater than what it would under com- 
mon circumstances have, according to the 
depth, to which the end of the ventilation 
pipe, is immersed in the water; and as this 
compressed state of the air, and the place’s 
thus having within it, more than it would 
under common circumstances contain, and 
being, as would vulgarly be said “ more 
than full,” is contrary to the natural ten- 
dencies of air, its expansive principle will 
be exerted, and every crack, and crevice 
about the place, will become a channel, 
to let air out instead ot'into it; and, in con- 
sequence, drafts into the place effectually 
prevented, owing to every cranny, through 
which they used to enter, becoming a chan- 
nel of egress instead of ingress. 
This is the way in which I prevent and 
do away with “ drafts and when the door, 
and ventilation apparatus (which is in fact, 
nothing more than a most sensitive valve, 
and to which, a valve, would, under some 
circumstances, be preferable) are well ar- 
ranged, and their effect not counteracted, 
by any of the cracks and crevices which are 
about rooms, being suffered to remain un- 
luted, or otherwise unstopped, it will be 78 
found most efficient, and the evil it is in- 
tended to remedy, effectually done away 
with. 
There is, to be sure, both singularity, and 
a degree of inconvenience, in a door-way 
such as I have described; though, as 
by having the pannels, of the revolving 
leaves, of glass, this might be much done 
away with; and as there is no other equally 
convenient way, of preventing all possibility 
of annoyance from the door, whenever any 
one either entered, or went out of the place, 
it might be submitted to, should common 
doors not be considered sufficient. 
With the prevention of inconvenience, 
and the danger of taking cold inside the 
place, would also be the removal of much 
of the liability to cold, &c. when leaving, 
the now highly heated atmospheres of pub- 
lic places. As, owing to the temperature's 
being always uniform, and never above that 
which was agreeable and salubrious, much 
of the danger we all experience, and many 
of the indispositions people of delicate con- 
stitutions incur, in consequence of passing 
from the now (again to admit a vulgar 
idiom) almost “ melting" atmospheres of 79 
public places, to the open air, would be 
done away with. 
The measures I take to warm the air 
which would be injected, it will be but 
waste of time to describe; it being suffi- 
ciently evident, that there are plenty of 
ways of doing this. Merely observing, there- 
fore, that availing myself of an apparatus 
I several years ago invented—of the high 
temperatures,which the fixed oils bearwith- 
out vaporization—and (it may be) taking 
advantage, of an opportunity which the pro- 
cess would offer, of facilitating the heating 
the air, by somewhat increasing its capacity 
for caloric by slight rarefaction, I warm the 
air to whatever may be agreeable prior to 
injecting it, I dismiss this portion of the 
subject. 
And having thus shewn the whole course 
of ventilation entirely in our hands, I might 
conclude, were it not, that the measure of 
exclusive appropriation to which I have 
been driven on the subject, renders it ne- 
cessary, to enter on some detail, as to the 
cause of that measure. 
It is now nearly four years, since I have 
seen it impossible by the present method 80 
of ventilation—that is, by permitting the 
air to enter and pass off, at, as it were, its 
own pleasure, either to preserve uniformity 
of temperature in any place of public con- 
vention, or to prevent drafts; and since I 
have endeavoured to gain public attention 
as to the only method by which these de- 
siderata can be attained—that is, artificial 
ventilation—or ventilation, by the air's be- 
ing first, cooled, or warmed, as the season 
dictated, and then mechanically injected, 
instead of being suffered to enter, and leave 
the building, as the temperature, and con- 
sequent levity, of the respired and heated 
air, and the size of the ventilation aperture 
regulated. 
As, however, my first view of the subject, 
confined itself to the application of the prin- 
ciple to the ventilation of the Houses of 
Parliament, I did not attempt any thing 
more, than the getting it brought upon 
their notice, under the patronage of a mem- 
ber of the Upper House, who considered 
what I proposed, as important, if practica- 
ble. But, as, to carry the thing through, 
required more fostering than he, and more 
solicitation, &c. (to those to whom it was 81 
necessary to apply) than I chose to give if, 
nothing resulted, other than a debt of gra- 
titude to the noble individual by whom I 
had been countenanced; and in the state 
in which it was thus left* it remained until 
about twelve months since, when, circum- 
stances apparently favourable to its being 
moved in occurring, I again endeavoured 
to get it taken up. But, as occurrences 
during this interval, had both given me ad- 
ditional confidence as to its practicability, 
and caused me to perceive, that the places 
in which its application would be the great- 
est relief, were the courts of Law, I deter- 
mined to bring it more publicly forward, 
and to attempt interesting those whom it 
would most benefit, in its behalf. 
But being in this also unsuccessful,* and 
having then (as a nameless, and unknown 
individual) no other course left, soon after 
* As some of the repulses I met with, were founded 
upon the room it would require, and others, upon the (as it 
was termed) impossibility of manufacturing apparatus, on 
a scale of sufficient magnitude, &c. Bcc. it may be as well to 
observe, that, as to the first, it will take up no room what- 
ever in the place to be ventilated, the principle (like that of the commencement of last session, I tried 
the sole remaining resource, of petitioning 
Parliament on the subject, (See App.) and 
failing also in this, as I had then done all 
I could to benefit the public without re- 
ference to myself, and as the repulses I had 
met with, had somewhat cooled my ardour 
for, and opened my eyes to the folly of 
coming forward, as anxious for the public 
benefit only, I determined to make my 
own advantage the primary consideration ; 
and accordingly, sued out a patent for it. 
Owing to a series of repulses therefore, the 
whole of which, at the periods of their oc- 
currence, ran directly counter to, and were 
gas works) admitting of the operation’s being performed 
cither upon, adjoining to, or at a distance from the pre- 
mises, according to convenience: and, as to the second, 
though there will be some difficulties of preparation to en- 
counter, yet, that they are no more, than the casting receiving 
cylinders, of a rather unusual size and substance—the pre- 
paring, somewhat novel machinery and tools, for boring, 
turning, and fitting up, the condensing cylinders, and pis- 
tons—and the a, b, c, work, of putting Professor Leslie’s 
principle in execution, on a scale of the greatest magni- 
tude, instead of on a table scale—in other words, building 
a ship of the line, instead of a fishing boat. 83 
the very reverse of, my wishes and efforts, 
I am become possessed of the sole right of 
operating in a way, which, if 1 see correct- 
ly, will be, not alone important to ourselves 
at home, but also important, and that too 
in the highest degree, to some of our foreign 
possessions. Of this am I, in consequence 
of many disappointments, and a long series 
of repulses and denials, become possessed. 
In what degree the good, which fortune has 
thus, in spite of myself bestowed upon me 
is to be estimated, it would be difficult to 
decide. Though, as, should what I pro- 
pose, have the effects I suggest, it wrould 
become matter of public interest; and, as a 
private individual's exercising control, over 
matters of public interest, is altogether 
foreign to the spirit of our constitution, 
should the suggestions I have risked, be so 
borne out, as to render the subject at all 
nationally important, I shall be prepared, 
becomingly to defer toThe opinions, of 
the guardians of the public welfare, with 
reference to it. 
THE END. 84 
APPENDIX. 
To the Honourable, the Commons, of the United King- 
dom of Great Britain and Ireland, in Parliament 
assembled. 
The. humble Petition of John Vallance, of Brighton, 
* 
in the county of Sussexp 
Sheweth, 
and invented corresponding apparatus, by which public 
buildings, such as your Honourable House, the Right 
Honourable the House of Lords, and the courts of public 
justice of the kingdom, may be freed from the distressing 
heats, and unhealthy atmospheres, sometimes experienced in 
them, and kept constantly cool, and of a pleasant, and 
agreeable temperature, at all times of the year, even during 
the dog days; and that, as the heated and deteriorated at- 
mospheres of the courts of justice, undermine, and operate 
as slow poisons, as well upon the constitutions of the Dig- 
nitaries of the Bench, as of those, learned in the law, who 
conduct the proceedings of those courts; and this, indepen- 
dent of the inconvenience, occasioned to such of the magis- 
tracy, and gentry of counties, as attend the courts of assize: as 
these circumstances, render your Petitioner’s discovery, in 
his own humble opinion, a national object, he prays, the be- 
ing allowed to prove, before a Committee of your Honour- 
able House, the perfect practibility of it, that your Honour- 
able House, may thereon direct such measures, as to your 
wisdom may seem meet, 
That your petitioner, hath discovered a method, 
And your Petitioner, Bcc. 
The Petition to the Lords was not presented, owing 
to the Peers to whom I applied, recommending that it 
should not. 
Printed by J. F. Ilove, St. John's. Square.