AN ADDRESS 
ON THE 
Climatology of Florida, 
DELIVERED BEFORE THE 
MEDICAL ASSOCIATION 
OF THE 
STATE OF FLORIDA, 
At their Annual Meeting, held in the City of Jackson- 
ville:, ON THE 171'H AND i8tH FEBRUARY, 1875, 
BY 
A. S. BALDWIN, M.D., President. 
CHARLESTON, S. C. * 
WALKER, EVANS & COGSWELL, PRINTERS, 
Nos. 3 Broad and 109 East Bay Streets. 
I875- AN ADDRESS 
ON THE 
Climatology of Florida, 
DELIVERED BEFORE THE 
MEDICAL ASSOCIATION 
OF THE 
STATE OF FLORIDA, 
At their Annual Meeting, held in the City of Jackson- 
ville, ON THE 171'H AND I 8th FEBRUARY, 1875, 
BY 
A. S. BALDWIN, M.D., President. 
CHARLESTON, S. C. 
WALKER, EVANS & COGSWELL, PRINTERS, 
Nos. 3 Broad and 109 East Bay Streets. 
1875. AN ADDRESS 
ON THE 
CLIMATOLOGY OF FLORIDA. 
Gentlemen of the 
Medical Association of the State of Florida: 
As many friends, for whom I entertain a high regard, 
have solicited it, and with whose wishes I am disposed to 
comply, I have chosen Climatology, or rather the Meteor- 
ology of Florida as the subject of an address which this 
Association requires annually from its President. 
While sensibly conscious of my inability to do full jus- 
tice to so important a subject, I am still willing to make 
any contribution in my power towards the elucidation of 
it, and the establishment of a better knowledge of our 
climate among the Profession and .others interested abroad, 
and among whom, after so much has been written and 
disseminated, a great variety of opinions seems still to exist, 
even while our neighbours of the North and West, in 
considerable and constantly increasing numbers, are mak- 4 
ing our State a winter resort, and, in many instances, a 
permanent abode. And why is there such a want of 
correct information, in regard to Florida, her topography 
and resources, her soil and productions, and of the true 
character of her climate, as it affects mankind, residing 
summer and winter, and year after year, within her bor- 
ders? Hitherto scores of invalid visitors have kept partial 
meteorological records during their winter sojourn here, 
and have been sending them to their respective homes for 
publication, accompanied by such comments and im- 
pressions as their state of health and feelings might at the 
time dictate. Sometimes favorable impressions were con- 
veyed, and sometimes the reverse, and these conflicting 
reports, seem to have produced upon the minds of medical 
men, as well as of others, an impression that our climate 
was fickle, and as variable as were the reports concerning it. 
Hence, it is important that whatever of reliable meteorolo- 
gical data we may possess, should be collected and sub- 
jected to an analysis, and put into a shape that shall 
impart the requisite information, and correct the false 
impressions which seem to have been made from unreliable 
reports based on very imperfect data. In an endeavour to 
accomplish this, I have been able to obtain numerous 
records of meteorological observations made at various 
stations in East and South Florida, but one from the 
Middle, and from but two in West Florida. These, added 
to my own observations for the past thirty-six years, com- 
prise the material from which I propose to work out the 
problem imposed upon me as my task on this occasion. 
We will first determine what is meant by the term 
climate ? 
According to Humboldt: “ The term climate, taken in its 
more general sense, indicates all the changes in the atmos- 
phere, which sensibly affect our organs as temperature, 
humidity, variations in barometrical pressure, the calm state of the atmosphere, or the action of opposite winds, 
the amount of electrical tension, the purity of the atmos- 
phere, and its admixture with more or less noxious gaseous 
exhalations, and, finally, the degree of ordinary transpa- 
rency and clearness of the sky, which is not only impor- 
tant, with respect to the increased radiation from the earth, 
the organic development of plants, and the ripening of 
fruits, also, with reference to its influence on the feelings 
and mental' condition of men.” 
“ Reclus” gives the following as his definition : “ All 
the facts of physical geography, the relief of continents 
and of islands, height and direction of the system of 
mountains, the extent of forests, savannas and cultivated 
lands, the width of valleys, the abundance of rivers, the 
outline of the coasts, the marine currents and winds, and 
all the meteoric phenomena of the atmosphere, vapours, 
fogs, clouds, rains, lightning, and thunders, magnetic cur- 
rents, or as Hippocrates said, more briefly, “ The places, 
the waters, and the airs," constitute in connection with lati- 
tude and longitude, what is called a climate.” These defi- 
nitions are sufficiently comprehensive to cover the entire 
subject, and they give a full enumeration of the different 
factors or elements of climate. The first, in Humboldt’s 
enumeration is, “ Temperature.” To elucidate this, we 
have ample materials, and to make it clear and easily un- 
derstood, I have tabulated the abstracts of mean tempera- 
ture taken at seventeen stations, besides my own. (See 
Appendix.) The names of the stations, their latitude and 
longitude is given, and the number of years and parts of 
years, during which these observations were made, are 
also given, and I have also added to the tables and enclosed 
in brackets the abstracts of other observations since the 
following deductions were made, and which do not enter 
into them. From this table we learn that the mean tem- 
perature of the spring for the entire State is 7i°62; for 6 
the summer, 8o° 51; for autumn, 710 66; for winter, 60 0 04; 
and for the year, 70° 95. And for the stations on latitude 
82° N, and south of it, for the spring, we have 740 94 ; 
for summer, 8i° 93 ; for autumn, 76° 57 ; for winter, 63° 
69 ; and for the year, 740 87. For the stations north of lat- 
itude 28° N, we have for the spring, 70° 66; for summer, 
8o° 10; for autumn, 70° 23; for winter, 58° 29; and for 
the year, 69° 82. There is not exhibited any great differ- 
ence between the northern and southern portions of the 
State, but enough to afford a choice of temperature during 
the different seasons, if the visitor desires change. During 
the spring, the temperature south of 28° latitude, is 40 28 
higher; and for summer, i° 83 ; for autumn, 6° 34; and 
for winter, 5° 40 higher than it is north of lat. 28°. 
It will be observed, that the temperature south of lati- 
tude 28° is in winter 5°40 higher than north of 28°, but 
that in summer it is only i°83 higher, showing that the 
difference between the summer and winter temperature, is 
less south than north of 28°. This is due to an astro- 
nomical law, which will be referred to more particularly 
hereafter; no reasonable objection can be urged to the 
temperature in any part of the state for the entire year. 
Meteorology may be said to be founded on the fact, that 
the rays of the sun constitute a force, which produces 
nearly all the changes which take place on the surface of 
the earth. The forces of the earth itself, such as gravity, 
chemical affinity, cohesion, electricity, or magnetism, etc. 
are forces of quiescence, that tend to bring matter to a 
state of rest at the surface of the earth, from which, it is 
only disturbed by the solar emanations. All elementary 
substances which constitute the surface of our planet, 
with the exception of organic matter, have long since gone 
into a state of permanent combination, and seems to have 
passed through intense heat, at some remote period of the 
past. “ The whole earth,” says Professor Henry, “ is an 7 
immense slag, analagous to that drawn from the smelting 
furnace, surrounded by a liquid and aerial envelope. The 
former in a state of ultimate chemical combination, and 
the active principle of the latter, oxygen, finding nothing 
to combine with, except what has been released from for- 
mer combinations, by the action of the sun.” If, there- 
fore, the solar impulses were suspended, all motion on the 
surface of the earth would cease, the aerial and the ocean 
currents would stop, and silence and death would reign 
supreme. The earth in her revolutions around the sun 
describes not a circle, but an ellipse, in one of the foci of 
which, is placed the sun, so that we are nearer the sun at 
one part of the year, than at another. It has been mathe- 
matically shown that the earth, as a whole, receives the 
greatest amount of heat from the sun on the first day of 
January, and the least on the fourth day of July (not on 
our hemisphere, but on the whole earth.) 
The variation of the distance of the sun from the earth, 
however, produces no effect on the different seasons, as 
many suppose, since the rapidity of motion, or the shorter 
duration of proximity to the sun, just compensates for the 
greater intensity of the sun’s rays, due to the near ap- 
proach. Owing to the spherical form of the earth, the 
sun’s rays strike it obliquely at all places, except those 
over which the sun is vertical, and where his rays are per- 
pendicular, and it is these vertical rays alone that produce 
results. The intensity of the rays will be greatest over 
the equatorial regions during the year as a whole, and will 
diminish to the poles. 
The sum of all the vertical rays from the rising to the 
setting of the sun, on any day, will represent the whole 
intensity of the heat of the sun on that day, received on 
any parallel of latitude on the earth, and in this way may 
be calculated the relative amount of heat received on dif- 
ferent latitudes at different seasons of the year; from this 8 
estimate we shall find that the amount of heat received, 
during any given day of summer, from the sun, at differ- 
ent northern latitudes, is greater than that which falls on 
the equator during the same time. This is shown in a table 
found in L. W. Meech’s paper, “ on the Sun’s Intensity,” 
published in the Smithsonian contributions in 1855, which 
table will be found in the Appendix. On the 15th of 
June, the sun is more than 230 north of the equator, and, 
therefore, it might be readily inferred that the intensity of 
heat should be greater at this latitude than at the equator, 
but that it should continue to increase beyond this, even 
to the pole, as indicated by the table, may not, at first sight, 
seem so clear. It will, however, be understood, when it is 
recollected that the table indicates the amount of heat 
received during the whole day; and though in a more 
northern latitude, the obliquity of the ray is greater, and 
on this account the intensity should be less, yet the longer 
duration of the day is more than sufficient to compensate 
this effect, and to produce the result exhibited, an increased 
amount of heat. And although there is more absolute 
heat at Jacksonville, Florida, during the entire year, lati- 
tude 30° 20, than there is at Milwaukie, Wisconsin, latitude 
43° °3> yet there is more heat received from the sun at the 
latter place, during the three summer months, than at the 
former, during that period, and Wisconsin is liable to expe- 
rience a higher temperature during the summer months, 
than is Florida during the same time. 
An analagous, but contrary result, is exhibited in regard 
to the cold of winter, as will be seen by the tables append- 
ed. It is on this principle that, as we come from the north 
towards the Equator, we find the extreme variation of the 
seasons becoming less and less as we advance. The curve 
representing the sun’s intensity very nearly corresponds 
with that of temperature in the Equatorial regions, but it 
becomes more bent in comparison as we proceed north. Upon this fact the greater equibility of the temperature of 
Florida is established over all places north of it, so far as 
astronomical influences can effect it, and not as liable to 
extremes of heat in summer, nor of cold in winter. 
There are other causes, however, not astronomical, which 
materially modify temperature in all latitudes, and we must 
determine if any of these influences are in operation here, 
and if so, what effects are produced. 
What becomes of the heat received on the earth from the 
sun’s rays? Heat is indestructible, and if it continues to 
accumulate on the earth’s surface, it will soon become so 
intense as to render it an unfit residence for man, animals, 
or plants. Although not in the order which I first intend- 
ed to discuss this element of climate, yet the theory of 
radiation of heat may very properly be introduced here, 
in answer to the above interrogatory—what becomes of 
the heat ? 
It is a well established fact that all bodies are radiating 
heat, even while they are receiving it. If the amount re- 
ceived in a definite time, is greater than that given off, the 
temperature will increase. On the contrary, if the amount 
given off, is greater than the amount received, then the 
temperature will decline. The earth is constantly radiat- 
ing heat into space, but only receiving it from the sun dur- 
ing the day. The rays of the sun are rays of high intensity, 
and have great penetrating power, but the rays which the 
earth gives off, are of low intensity, and have feeble pene- 
trating power, unless the heat is accumulated so as to make 
it intense. For example, those of high intensity will pass 
through the glass of a window into a room, and heat up 
the articles in it, if they are not good conductors of heat. 
The articles in the room will begin also to radiate heat, but 
of low intensity, which cannot pass back through the window, 
hence the room acquires and maintains a high temperature 
from the accumulated heat received and not given off. 10 
The atmosphere which envelopes the earth produces a 
similar result. The rays of the sun are transmitted through 
it to the earth, which in turn emits rays of low intensity 
that do not so readily penetrate and pass through this 
atmospheric envelope, but give rise to an accumulation of 
heat at the surface. The resistance to the transmission of 
heat of low intensity, depends upon the quantity of vapor 
in the atmosphere, and perhaps, also, to the density of the 
air itself. The radiation of the earth, therefore, differs 
very much on different nights and in different localities. 
In places where the air is very dry, the heat of the day is 
excessive, notwithstanding the radiation which is going on, 
but the nights become very cool. Gen. Emery, in his report 
on the Boundary survey, states that on some of the arid 
plains over which he passed, there was a difference of 6o° 
between the temperature of the day and that of the night; 
the air was so dry here that heat of low intensity would 
be radiated, so that on one occasion, when the camp ground 
was chosen in a gorge, between two steep hills, the inter- 
radiation between them, prevented the usual fall of the 
thermometer, and it stood several degrees higher than on 
the plain but a few rods off. Prof. Tyndall, who belongs 
to a new school of philosophers, in an article on radiation, 
uses the following language : “ The observations of meteor- 
ologist, furnish important, though, hitherto, unconscious 
evidence of the influence of this agent, (vapor in the air.) 
Whenever the air is dry, we are liable to extremes of temper- 
ature. By day, in such places, the sun’s heat reaches the 
earth unimpeded and renders the maximum high; by 
night, on the other hand, the earth’s heat escapes unhin- 
dered into space, and renders the minimum low, hence the 
difference between the maximum and minimum is greater 
where the air is dryest. Wherever drought reigns we 
have the heat of the day forcibly contrasted with the chill 
of the night. In the Sahara, itself, when the sun’s rays 11 
cease to impinge on the burning sands, the temperature 
runs rapidly down to freezing, because there is no vapor 
over head to check the calorific drain. And here another 
instance might be added to the number already known, 
in which nature tends, as it were, to check her own excess. 
By natural refrigeration, the aqueous vapor of the air 
is condensed to water on the surface of the earth, and as 
only the superficial portions radiate, the act of condensa- 
tion makes water the radiating body. Now experiment 
proves, that to the rays emitted by water, aqueous vapor 
is especially opaque. Hence, the very act of condensation 
consequent on terrestrial cooling, becomes a safeguard 
to the earth, imparting to its radiation that particular char- 
acter which is most liable to be prevented from escaping 
into space. 
It might be argued, however, that inasmuch as we de- 
rive all our heat from the sun, the self same covering, 
which protects the earth from chill, must also shut out the 
rays of the sun. This is partially true, but only partially. 
The sun’s rays are different in quality from the earth’s 
rays, and as it does not follow that the substance which 
absorbs the one, must necessarily absorb the other. 
Through a layer of water, for example, one-tenth of an 
inch in thickness, the suns rays are transmitted with com- 
parative freedom, but through a layer of half this thick- 
ness, as Meloni has proven, no single ray from the warmed 
earth could pass. In like manner, the sun’s rays pass with 
comparative freedom through the aqueous vapour of the 
air, the absorbing power of this substance being mainly 
exerted upon the heat that endeavors to escape from earth. 
In consequence of this differential action upon solar and 
terrestrial heat, the mean temperature of our planet is 
higher than is due to its distance from the sun. A cobweb 
spread over a blossom is sufficient to protect it from 
nightly chills, and thus the aqueous vapour, attenuated as 12 
it is in our air, checks the drain of terrestrial heat and saves 
the surface of our planet from the refrigeration which would 
assuredly accrue, were no such substance interposed be- 
tween it and the voids of space.” 
I have dwelt longer on this particular element of climate 
than I would have done, had not one of the principal ob- 
jections to our climate been its “ excessive humidity,” and to 
meet this objection I have made lengthy quotations from 
authorities, from which it appears that humidity in the 
atmosphere is essential to protect us from those extreme 
diurnal changes of temperature which so seriously detract 
from those climates where they exist, and where the 
diurnal changes exceed the range that I have ever recorded 
between the maximum and minimum of a month, when 
several days, or weeks, perhaps, had intervened between 
the extreme high and low temperature; indeed, the differ- 
ence between the highest and lowest that I have recorded 
in thirty-six years, is not so great as is the diurnal differ- 
ence in many places where a very dry atmosphere exists. 
I give an abstract of my own records, for the months of 
November, December, January, February, and March, five 
months, as deduced from several years’ observations. The 
mean diurnal range for November is I3°4 for December, 
I3°9; for January, I4°4; for February, i4°o; for March, 
I4°9. These are the five months in which visitors are par- 
ticularly interested, and they are also those in which the 
greatest diurnal variation occurs during the year. 
The average number of frosts for the month of January, 
in Jacksonville, in twenty-seven years’ record, is 5.4; for 
February, 3.1 ; for March, 1.3 ; for April, 0.2 ; and no more 
until October, 0.2; for November, 2.3 ; for December, 5.2. 
The first frost in the Fall has occurred in October, four 
times ; in November, sixteen times ; in December, seven 
times ; and twice the second frost has occurred in Febru- 
ary. There have been several years in which no frost occurred in October ; there have been years in which none 
have occurred in November or December. There have 
been years when no frosts occurred in January, none in 
February, still more in which March was exempt; very few 
frosts have occurred in April, and none after. In 1858, a 
frost occurred on the 28th of April, which is the latest 
recorded; and there have been but four Aprils in which 
frosts have been recorded; and there have been but four 
Octobers in which they have been recorded. From these 
statements, an idea can be formed of the average amount 
of freezing weather in winter. December and January are 
the oftenest visited with frosts, a little over five times in 
each month on an average. 
As clearness of sky is connected with the subject of 
radiation, and is also an important element of climate, it 
will be introduced here. I have, in making up my results, 
of which I propose to present an abstract, counted those 
days clear which were marked from o up to 5, the latter 
representing the sky half covered with clouds. The month 
of January, from twenty-two years’ observations, has had 
an average of 20.3 clear days ; February, for twenty-five 
years, 19.5 ; March, for the same period, 20.4; April, 25 , 
May, for twenty-six years, 22.1 clear days; June, for 
twenty-five years, 17.1 ; July, for the same period, 18.5; 
August, for twenty-six years, 19.1 clear days; September, 
for twenty-four years, 17.2 ; October, for twenty-five years, 
19.2; November, for uventy-four years, 20.0; December, 
for the same period, 20 clear days. For Spring, the ave- 
rage is 63.7; for Summer, 55.1; for Autumn, 56.4. for 
Winter, 59,8 ; and for the year, 235 clear days out of 365, 
leaving 130 days in which the sky was more than half 
covered with clouds, and on some of which rain has fallen. 
In January, there has been an average of 6.6 rainy days ; 
in February, 3.6; in March, 5.7; and in December, 5.4 
rainy days, and these constitute the four months in which 14 
visitors are especially interested. In these months we 
have an average of 21.3 rainy days out of 121 days. 
I have not calculated the results for the other stations in 
the State in relation to this subject, but from a pretty care- 
ful examination of them, I judge that the results would 
not materially vary from what I have given from my own 
tables : and, on the whole, the preponderance of clear over 
cloudy and rainy days, speaks decidedly in favor of our 
climate, as being characterized by a fair amount of plea- 
sant weather. The term relative humidity, as used in our 
meteorological tables, is calculated to produce on the 
minds of those who have not especially informed them- 
selves of its real value, in absolute moisture, which is con- 
tained in the atmosphere, a very erroneous impression. 
When the temperature is 50°, the barometer 30.00, and 
the relative humidity marked 100, there is in one cubic 
foot of air only about four grains of water. If the tempera- 
ture is ioo°, the barometer the same as before, 30.00, and 
the relative humidity still recorded 100, a cubic foot of air 
will contain 20 grains of water. Now if the temperature 
is again reduced to 50°, the barometer the same, 30.00, and 
the relative humidity recorded still 100, the cubic foot of 
air will have parted with 16 grains of water, and it will be 
still saturated, although it contains but four grains, only one- 
fourth of the weight of water that it did at the tempera- 
ture of ioo°. Very few would appreciate this difference by 
looking at the record; if they have relative humidity 
recorded at 100, they would, without understanding it, pro- 
nounce the climate a very damp one, and this, no doubt, 
has led many to believe this climate to be excessively damp, 
as it has often been considered. Let us reverse the calcula- 
tion just given ; suppose instead of the temperature being 
50°, it was ioo°, and there was no accession of moisture, 
the cubic foot of air would contain four grains of water, while 
a cubic foot of air is capable of containing 20 grains at 15 
that temperature, it is clear that four grains will only satu- 
rate one-fourth of it, and one-fourth of IOO would be 25 ; 
and if many should see in the column of relative humidity 
the record 25, they would be very well satisfied that this 
was a very dry climate, and yet there is no less absolute 
moisture in it than there was when recorded 100, and the 
temperature 50°. 
I have been thus particular in endeavoring to place this 
matter in a clear light, because it has been the cause of 
much disparagement of our climate, from the fact that the 
term relative humidity has not been understood by the 
objectors. I have determined from my own tables the 
relative humidity approximately by taking the mean tem- 
perature of the month, and the average difference between 
the dry and wet bulb thermometers, the mean of the dry 
bulb being the same as the mean temperature of the 
month, and with these I deduce the relative humidity by 
the assistance of the tables provided for the purpose, and 
the following is the result: for the month of January, the 
relative humidity is 67.20; for February, 67.15 ; for March, 
57.50; for April, 63.20; for May, 62.60; for June, 73.3; 
for July, 74.7 ; for August, 73.4; for September, 76.8 ; for 
October, 74.4; for November, 71.5; for December, 74.0; 
for Spring, 61.0; for Summer, 73.8; for Autumn, 74.2; 
for Winter, 69.4; for the year, 69.6; the annual and winter 
mean being nearly the same, showing a considerable 
amount of moisture in the atmosphere, but by no means 
an “ excessively damp climate,” for the annual mean shows 
that upon an average there is but (5.7) five and seven-tenths 
grains of water to the cubic foot of air, not deleterious to, 
or uncomfortable for respiration, and keep the air passages 
properly lubricated, but enough to prevent those great 
diurnal extremes of temperature so deleterious to the health 
and comfort of mankind. Here, as well as elsewhere, 
where rain falls, there must be times when the air is fully 16 
saturated, else there could be no precipitation, and agri- 
culture, or fruit-growing, could not be prosecuted to advan- 
tage, nor would it be a comfortable residence for man. 
In its topography, Florida presents no mountains and 
no elevated plateaus exceeding three hundred feet above 
the sea, by which it is bounded on all sides, except on its 
northern border; but it is not, as many times represented, 
a low, flat, marshy country, for in many portions its surface 
is undulating and rolling. Its area covers 59,248 square 
miles of pine land, oak hammocks, flat savannas, nume- 
rous clear fresh water lakes and rivers, which add beauty 
to the landscape, comfort, pleasure, and subsistence to the 
inhabitants in their vicinity, for most of the two latter are 
liberally stocked with fine varieties of fish. Many of our 
springs, and small lakes even, are artesian, and rise from 
the substrata of rocks upon which the arable soil is based, 
and pour out copious streams of water to augment the 
volume of our rivers, which discharge into the sea. The 
probable sources of these are in the higher lands, on our 
northern border, and are supplied by the rainfall of neigh- 
boring States. The State is, in some portions, traversed 
by subterranean streams of considerable size, whose course, 
in many instances, is marked by the line of funnel-shaped 
sinks, where the sand above the rocky strata has filtered 
down through abrasions of the rocks, and has been carried 
off by the current beneath, leaving the sink, at the bottom 
of which water is always present, and in many of which fish 
are abundant. Most of these subterranean streams have 
their outlets in the springs above described, but some are 
known to discharge into the sea off the Atlantic coast of 
the Peninsula, and with sufficient force to displace the 
denser salt water, so that fresh water has often been ob- 
tained at sea, simply by drawing it up in buckets over the 
vessel’s sides. Many of these artesian fountains are mine- 
ral ; sulphur, iron, magnesia, lime, etc., being the constitu- 17 
ents. There are but few extensive marshes in the State. 
At the sources of the rivers, on the summits, are often 
found savannas, covering many acres, but they do not, like 
the marshes and savannas in many other countries, consist 
of deep alluvial deposits, which have been brought down 
from higher elevations, because these are the summits 
themselves from which the water supply of the rivers come. 
This is a peculiarity in Florida, and the residents around 
these savannas are not specially liable to diseases of a 
malarial character. That large area on the lower end of 
the Peninsula, called the Everglades, and covered by water, 
is by many supposed to be marshy ; but such is not the 
fact, for it is simply a shallow lake, elevated above the ocean 
some ten or more feet, surrounded by a rocky rim, with a 
sandy and rocky bottom, containing clear fresh water, 
which is discharged through fissures or apertures in the 
rocky rim into Key Biscayne Bay, and probably through 
outlets on the west side into the Gulf. At the north of 
the Everglades is Lake Okechobee, the largest body of 
fresh water in the interior of the State. It is fed by the 
Kissimee River, whose source is in the same savanna, or 
summit level which is the source of the St. John’s River. 
Its outlet is into the Everglades. Interspersed through 
this savanna, and that at the head of the Oclawaha River, 
are numerous lakes, which, by modifying and equalizing 
the temperature, render the country around their borders 
peculiarly adapted to the culture of oranges and other 
tropical fruits, while at the same time the residents in gen- 
eral enjoy good health, both summer and winter. 
There are here, as well as in every newly opened country, 
some localities where diseases, termed malarial, will for a 
time prevail, but are here of a mild form and easily managed. 
Having alluded in this general way to the topography of 
the State, we will now give an abstract of the rainfall, the 
materials for which consists of records from nine stations 18 
in the peninsula, and two in West Florida. I regret that 
I have none from the middle district. From my own 
experience here, I am satisfied that to be able to determine 
satisfactorily the amount of rain which falls on any locality, 
the observations should be extended over a period of at 
least ten years, in order to obtain a fair mean, for I can 
select from my own tables one, two, and three years, and 
which sometimes come in succession, that are peculiarly 
dry years, or peculiarly wet ones, from which, if a mean 
was struck, it would not be a fair average. Our so-called 
rainy season, though sufficiently marked to warrant the 
designation during most years, is not always so well 
defined. It generally embraces a period of about sixty 
days and ordinarily commences about the middle of June, 
and terminates about the middle of August, but it oscillates 
from May to September. Sometimes the rainy season 
apparently commences, and perhaps daily showers will 
recur regularly for one or two weeks, or more, and then, 
perhaps, weeks of clear, settled weather will be interpo- 
lated, and the rainy season will come on again, and con- 
tinue, so that about the usual complement of rainy days 
will occur. During the rainy season, the rain is by no 
means continuous, but comes in showers of from a half to 
one hour or more in continuance, and between the hours of 
from i to 4 P. M., sometimes, but not always, attended with 
thunder and lightning. 
Before the shower, the atmosphere may be hot and 
sultry, but afterwards the sun shines out, the air is pure, 
cool, and refreshing. The showers generally come with 
such regularity, that they need not interrupt business, 
labour, or pleasure, only during their continuance, for 
timely preparation to avoid them can be made if desired. 
Sometimes they are preceded by squalls of wind, which 
might endanger small crafts on the river, if ordinary pre- 
caution was not taken. Occasionally a fall of hail will 19 
result, if clouds from different directions meet, as is some- 
times the case, but instances where damage has been done 
to vegetation have been very rare. The moisture evaporated 
from the Gulf is the principal source of our summer 
showers. In the appendix will be found the table showing 
the rainfall of the State. Here are eleven stations scat- 
tered over the State. You will observe that in the Peninsula 
the stations of Fort Myers and Fort Pierce, the former 
on the Carloosahatche, on the west, and the latter on 
Indian River, on the Atlantic, furnish the largest amount 
of water. These show that the water shed supplying the 
Everglades, and the St. John’s receives the greatest rain- 
fall. Pensacola, in the west, receives the next greatest 
amount, and Tampa the next. Take Tampa, Fort Myers, 
and Fort Pierre, we have a rainfall of sixty inches during 
the year, and this district is marked sixty inches on the 
Hyetal charts, which have been constructed to show the 
rainfall of the United States, and in the West there exists 
another such region in the eastern portion of which, Pen- 
sacola is located. This is also marked sixty inches, and are 
the only localities in the United States, except one other 
on the Pacific coast, at the mouth of the Columbia River, 
Oregon, that is marked as high. The rainfall of the State 
north of north latitude 28°, and east of Pensacola, is about 
44 inches annually on the average. I have recorded an 
annual fall as low as thirty-five inches in Jacksonville, and 
as high as sixty-seven inches, hence, I conclude, that the 
mean given to St. Augustine, 31.80, does not represent the 
average rainfall of the place, and was deduced from one 
and a part of four years’ observations. The annual rain- 
fall of 1857, as reported by Dr. Mauran, was 40.85 inches, 
which is low in comparison with other stations, except 
P'ort Mead, which is 40.22 inches. There are causes 
which are known, that accounts for the smaller amounts of 
rainfall at St. Augustine. I have often, when on the sea 20 
islands, on the Atlantic coast, witnessed the influence which 
the sea breeze exerted in preventing the rain cloud ap- 
proaching from the west, from reaching the coast. 
I have, in the early summer, just after the rainy season 
had set in here, often gone to the islands, and not a drop 
had fallen there yet; nor on the main land which lay im- 
mediately on the coast; and I have seen the clouds ap- 
proach from the west or southwest, and would be arrested 
over the main land one or two miles distant, and in sight, 
and pour down rain freely for an hour or more, but not a 
drop would fall on the island where I was, and this action 
of the sea breeze no doubt accounts for the smaller amount 
of rainfall at St. Augustine, situated as it is on the coast. 
In a short time, however, the summer rains reach the coast, 
because the easterly winds become less prevalent in June 
and July than previously. I have also noticed that the 
winds and rain clouds were disposed to follow the course 
of the river, through its different reaches, during the sum- 
mer, sometimes to the advantage and sometimes to the 
detriment of those passing up and down in small boats. 
Rain, in many instances, will pour down on the river itself, 
while scarcely a drop will fall on the banks. I have often 
seen rain apparently falling on a point five miles above 
this city, but upon inquiry none had fallen there, or here, 
but there had been a smart shower on the river between 
the two places. I mention this fact now, as I shall use it 
hereafter to illustrate phenomena, which may have an im- 
portant bearing upon the climate of Florida. The amount 
of rain measured in any one locality may not give the 
exact amount which has fallen on the region around in the 
vicinity. There are several causes which may, and often 
do, produce discrepancies in the results of different ob- 
servers. An elevated rain gauge is not likely to measure 
as much as one on the surface of the earth, because when 
the air is saturated, a drop of rain passing through it, from 21 
the upper to the lower gauge, will increase in bulk during 
its passage, hence the lower one will measure the most- 
In the same place, with but few rods intervening, the re- 
sults given by two observers may be unlike. Showers in 
narrow lines often fall so that one gauge would have a sen- 
sible quantity for measurement, while over the other there 
was but a sprinkling of rain, and none to measure. The 
results given are, therefore, but an approximation to the 
exact truth, but taken through a long period of time the 
results may be considered entirely reliable if the measure 
has been properly placed. 
In order to be able to understand many other meteoro- 
logical phenomena, it will be necessary to have at least a 
general knowledge of the laws which govern the barome- 
trical pressure of the atmosphere, and especially its relation 
to the theory of the circulation of the winds. The accu- 
mulation of the atmosphere over head causes barometric 
pressure, producing a rise of the column of mercury in the 
instrument. Now the atmosphere has the credit of extend- 
ing to various altitudes from forty to even two hundred 
miles, but it may be put at about fifty miles as the upper 
surface of the atmosphere. The lower strata being the 
most dense and becoming less and less so as we go up. 
The barometer at the sea level stands at 30.00 inches, 
and at 3.4 miles above the sea level the barometer stands 
at 15.00 inches, so that one half of the atmosphere in 
weight is below that level, and which is much below the 
top of many of our mountains,-and very much below the 
elevation to which balloons have attained. When air is 
heated, either by the direct influence of the sun, or by cur- 
rents of higher temperature, its particles expand farther 
than what is due to their relief from pressure, they become 
lighter and ascend higher into space, and spread out and 
flow off laterally. Under this column the barometer will 
fall because of the diminished pressure. The contrary 22 
takes place when the air is condensed by cold and when 
the aerial masses flow together to fill up the space left void 
by condensation, the weight of the column is increased 
and the barometer rises. A fall of the barometer, unlike 
that of the thermometer, indicates an increase, while its 
rise indicates a diminution of temperature. This is so 
much the case here in Florida that from the barometer 
alone, we obtain a close approximation to temperature, as 
well as atmospheric pressure. I have often amused myself 
in the construction of a diagram on which I have protracted 
the curves of the thermometer and of the barometer, 
making the figures of one increase from the top down- 
wards, and the other from the bottom upwards, and the 
parallelism thus shown between the curves was remarkable. 
But this was not so at the North and in New England, 
and this is another fact which shows ours to be the more 
equable climate. At the North, and in New England, pres- 
sure and temperature are both liable to frequent fluctuations 
and attended with storms of greater or less severity. This 
equability of pressure does not exist to the same degree as 
here, in the islands of the gulf south of us, for there, there 
are often sudden and rapid fluctuations, which indicate 
dangerous atmospheric disturbances, which portend or ac- 
company storms of a violent and cyclonic character, which 
take a spiral course, and under the influence of which we 
are occasionally, but very seldom, brought, at least here, 
on the base of the Peninsula. 
This parallelism of the barometer and thermometer 
curves, was noticed by Prof. Russell, an eminent Scotch 
meteorologist, who visited this country several years ago, 
and lectured at the Smithsonian Institution, Washington, 
and he found that it existed in the States south and west of 
the Alleghany range. The pressure of the atmosphere 
varies over different degrees of latitude. At the Equator, 
says Reclus, the barometer stands at about 29.84 inches, but 23 
from latitude io to 30, or 35 N., it increases so that it 
stands at or above 30.00 inches, and this after being re- 
duced so as to obtain the pressure only. I will here 
remark, that we are in this latitude, under the belt of high 
barometer, for the mean of my own observations shows, 
that the barometric pressure is about 30.100 inches, 
one-tenth of an inch above 30 inches. The results at 
the Signal station here, confirm this; at New Orleans 
and along this line of latitude, similar results are observed, 
and this belt of high pressure is the dividing line between 
the trade wind belt of the Tropics, and the belt of west- 
erly winds north of the trade winds. And a belt of high 
barometer divides the westerly wind belt from the Polar 
belt, to which I shall more particularly refer presently. 
There are other minor oscillations of the barometer which 
it is not necessary in this discussion to refer to, and I will 
now proceed to discuss one of the most important ele- 
ments of climate. The atmospheric circulation or the 
system of winds of the Northern Hemisphere, as they 
affect us in these latitudes. The sun here is the great 
motive power which destroys the equilibrium of the at- 
mosphere, and gives rise to all the currents which circulate 
over land and sea. In obedience to physical law, the 
repulsion of the atoms of the air are increased by being 
brought closer to each other by pressure, and it is also 
increased by the addition of heat. If water at ordinary 
pressure is converted into steam or vapour, a cubic inch 
of water is transformed into about a cubic foot of vapour, 
the atoms of vapour are, therefore, twelve times farther 
apart than when they were in a state of water. The action 
of heat has had the effect of putting every atom in a state 
of repulsion, with regard to its fellows. Every one tends 
to fly off from the other with as much force as if each 
was under the influence of a powerful spring. This in- 
tensity of the repulsion of the atoms constitutes the force of vapour. The density of the air at the surface, and its 
levity in the upper atmosphere, tends to produce an equi- 
librium of the whole atmospheric mass, but in a most 
delicate kind of balance, liable to be disturbed by the 
slightest accession of heat in any part of the mass. Un- 
derstanding this delicacy of balance, we proceed to de- 
monstrate what effect the addition of heat has on the 
general circulation of the atmosphere. 
The atmosphere within the tropics being heated, ex- 
pands and rises upwards, the denser air on either side, 
north and south, press in to fill the void made by the 
ascending column, and a surface current would thus be 
established back to the pole; the heated air at the equator 
rises up until the levity of the air above on each side will 
allow the ascending column to flow off laterally north and 
south to the poles; and thus we have an upper current 
from the equator to the pole established, which unites and 
becomes continuous with the surface current from the 
pole to the equator, and would continue to pass in this 
current continually, all the while endeavoring to restore 
the lost equilibrium. But these currents cannot restore 
lost equilibrium, because of the constant addition of heat 
at the equator, and the distribution of it towards the pole, 
and they cannot flow along the meridians in consequence 
of the rotation of the earth from west to east; but those 
at the surface will take a westerly course, while those 
above will flow in an easterly direction. When the upper 
current has reached the 30th degree of latitude, owing to 
the Spherical form of the earth, the meridians have so 
closely approached each other, that space sufficient is not 
allowed for the wind to flow in the same plane, and the 
result of this necessity is, that that part of the upper current 
is forced down to the earth, and returns back, mingled with 
the surface current, and makes the trade wind of the tropics ; 
and another portion in its conflict with the surface current 25 
creates a new belt of winds, which constitute the belt of 
westerly winds north of the trade wind belt, and a portion 
of the upper current still passing on until in consequence of 
the still diminishing space between meridians in the plane 
of the upper current, another descent is made to the earth, 
and the northern boundary of the westerly belt is there 
established, which is also the southern boundary of the polar 
belt, which extends to the pole, where the winds are south- 
erly. (I am of course referring to the Northern Hemis- 
phere.) This is the theory of the atmospheric circulation, 
described in my own language, as succinctly as possible, 
and now I propose to bring to bear upon this subject the 
result of an analysis of the observations taken at over six 
hundred stations on land on the Northern Hemisphere, 
made by Professor Coffin, in his great work on the winds 
of the Northern Hemisphere, and from observations innu- 
merable, furnished by the wind and current charts of the 
Atlantic and Pacific ocean, collected by Prof. Maury. 
Professor Coffin’s work was published as contributions 
to science, by the Smithsonian Institution, in 1850, in 
which there is shown great research, and an almost infinite 
amount of labour, and his results are now accepted in all 
parts of the civilized world, as reliable authority; and 
after concluding his labours, he modestly asks, “Do not 
the results authorize us to lay down the following, as a 
general description of the winds of the Northern Hemis- 
phere? 1st. That from high northern latitudes the winds 
proceed in a southerly direction, but veer to the west as 
they approach a limit, running from about latitude 56° on 
the western continent, to about latitude 68° on the eastern, 
where they become irregular and disappear. 2d. That 
further south, there is a belt of westerly winds, less than 
two thousand miles in breadth, encircling the earth; the 
westerly direction being clearly defined in the middle of 
the belt, but gradually disappearing as we approach the limits on either side. 3d. That south of the Zone last 
named, the mean direction of the wind is easterly.” Or in 
other words, he determined that in the northern belt, lie 
found that the winds were northerly, in the middle belt 
westerly, and in the tropical belt easterly. There were 
local influences in different localities to render the winds 
conflicting, and it was a difficult task to reduce them all 
to their mean normal direction, and establish the results 
which conform to the theory of atmospheric circulation in 
most particulars. There are some localities where the 
local influence predominates over the general, in giving 
direction to wind currents, of which he became fully aware. 
In making his reductions, he assumes that the wind in its 
normal course is one hundred, and in reducing conflicting 
winds to the normal course, that a certain amount of their 
force and velocity in moving in that course has been lost 
by conflicting forces, and the rate of progress given, is a 
fraction of one hundred. If for instance, we take St. 
Augustine, as reduced from four years observations of the 
direction and force of the wind at that place, the mean 
direction for the month of January, was found to be N. 90 
27' E., for February, S. 78° 53' E., for March, S. 810 52' 
E., for April, S. 740 32' E., for May, S. 65° 12' E., for 
June, S. 85° 29' E., for July, S. 6i° 5' E., for August, S. 
540 48' E., for September, N. 76° 42' E., for October, N. 
570 26' E., for November, N. 370 58' E., for December, 
N. 56° 13' E., and for the year, reduced to a mean was, N. 
790 19' E., being not quite two degrees N. of East, and the 
rate of progress was twenty “five, only one-fourth of the rate 
of its normal course. I give this as an illustration of his 
process of reduction, from months to yearly means. I put 
in tabular form, several points in Florida, in order to deter- 
mine the mean direction of the wind in all parts of the 
State, and will give the yearly means and the number of 
years covered by the observations; and here, as well as in 27 
other observations, it is desirable to have an as extended 
a series as possible, to obtain exact results. 
For St. Augustine, from four years’ observation, the mean 
direction was, N. 79019 E. Rate of progress, 25. 
For Fort King, from three years’ observations, the mean 
direction was, S. 4°50 W. Rate of progress, 17. 
For Tampa Bay, from six years’ observations, the mean 
direction was, S. 36°5 W. Rate of progress, n. 
For Pensacola, from seven years’ observations, the mean 
direction was, S. 23°48 W. Rate of progress, 19. 
For Cape P'lorida, from one year’s observations, the mean 
direction was, S. 47°59 E. Rate of progress, 20. 
For Carreysford Reef, from one year’s observations, the 
mean direction was, N. 82°25 E. Rate of progress, 32. 
For Indian Key, from one year’s observations, the mean 
direction was, S. E. Rate of progress, 47. 
For Tortugas Island, from one year’s observations, the 
mean direction was, N. 65°29 E. Rate of progress, 48. 
P"or Key West, from four years’ observations, the mean 
direction was, N. 78°6 Pk Rate of progress, 38. 
The mean direction of the winds at Pensacola, are up 
the valley of the Mississippi, and those next prevalent are 
down and towards the Gulf of Mexico. 
Those south of the 28th degree of latitude, when re- 
duced to a mean direction would be a little north of east 
or N. 8o°8 E., with a rate of progress of 35, would blow 
across the Gulf towards Mexico, and be deflected upwards? 
and would enter the valley as a southerly wind, while 
those north of 28th degree would be S. 38°4 E., would 
blow up the Atlantic coast towards the Alleghany range, and 
as their rate of progress would be but 10 they would 
not surmount the range, and would follow the coast to the 
east of the range. These results show that our winds 
partake of the monsoon characteristics, and in summer 
blow towards the land when it is heated. But the direc- 28 
tion of those above the 28th degree of latitude on the 
Peninsula blow up the Atlantic coast, but the rest are car- 
ried up the valley of the Mississippi, and this valley is one 
of those extended plateaus, which, when heated by the sun 
in summer, would draw the winds from the adjoining seas, 
to supply the void made by the rarification and ascension 
of heated air over its extended area. The influence of the 
valley of the Mississippi, upon the weather of the United 
States is much greater in my opinion than has been hereto- 
fore accredited to it. The valley is open on the south to the 
Gulf of Mexico, and is bounded on the west by the Rocky 
mountain range, which has a direction from south-east in 
the lower end of the valley to north-west, and extends to 
the polar basin in the north. At the lower and southern 
portion it has the Alleghany range for a boundary on the 
east, which has a direction from south-west to north-east, 
and its southern termination is as far west as the 89th degree 
of longitude, and west of any meridian that passes over 
Florida. 
This valley, however, does not terminate at the sources 
of the Mississippi River, but extends still northward until 
it reaches the polar basin ; no ridge of mountains cross 
the valley to separate the lower part from the polar basin, 
or prevent the winds of the polar regions from traversing 
its entire length; nor those from the Gulf of Mexico, 
which alternately move up and down this valley—the one 
cold and dry, and the other hot and loaded with moisture 
from the Gulf, the Caribbean Sea, and from the Equatorial 
regions of the Atlantic farther south. In this valley are 
exhibited some of the most interesting and remarkable 
meteorological phenomena that arise on the face of the 
globe, and which give character to the climate of the 
Northern, Middle, and New England States. In the sum- 
mer, this extended plateau is heated by the rays of the 
sun, the atmosphere being rarified and ascends, the rain, 29 
bearing winds from the Gulf and below, rush up the valley, 
distributing their rains which give it its wonderful fertility; 
which winds are, however, replaced, or alternated by those 
cold, disagreeable winds, termed the northers, which visit 
Texas, Mexico, and, in a modified form, Cuba and the 
other West India Islands, and perhaps the lower point of 
our Peninsula. These northers have heretofore been con- 
sidered deflected trade winds. But I am disposed to differ 
with those who have entertained this opinion—first, be- 
cause most, if not all, of this valley is not in the trade 
wind belt, but north of it, and in the belt of westerly winds, 
which has been shown by Professor Coffin to encircle the 
earth. I object, in the second place, to this view, because 
there is a more natural and simpler mode of explanation 
of the phenomena. I have observed, and so have many 
others, who have had their attention drawn to the matter, 
that winds are disposed to follow water courses, in well 
defined valleys, in preference to blowing across them. I 
have remarked previously that such was the case in the 
valley of the St. John’s, which is by no means as well de- 
fined a valley as many others. 
But Professor Coffin, in his efforts to reduce conflicting 
winds to their normal direction, found it very difficult, to 
do so, when well defined valleys existed, and this is the 
conclusion to which he arrived, after giving the subject more 
study than has been given to it probably, by any other 
man. Says he : “ In any well defined valleys of considerable 
extent, it is a well known fact, that the winds are influenced 
to take the direction of the valley. An example is given 
of the Hudson River Valley, where half of the winds or 
more follow the river up and down; and yet, (says he) 
the mean direction of the winds of the whole is nearly at 
right angle to it.” Now if we make application of this 
well established principle to the Mississippi Valley, which 
certainly is a well defined one, what is the result? As the 30 
winds of the polar belt have been shown to have a south- 
erly direction by Prof. Coffin, there is nothing to prevent 
their free entrance into that broad northern mouth of this 
valley, and the high wall of the Rocky Mountains on the 
western boundary of the valley for its entire length would 
tend to continue this direction to the Gulf of Mexico, and 
even beyond, for the mountains of Mexico, the Sierra Madre, 
are but the continuation of the Rocky Mountain range, 
extending to Central, and even South America, curving to 
the eastward, so as to embrace the Caribbean Sea, and 
then taking a southern direction, and joining the Andes. 
This is the course taken by the polar winds, and they 
constitute the northers, which are cold and disagreeable, 
and these polar winds also are probably the main cause 
of those sudden atmospheric disturbances which are gen- 
erated so frequently in the sea of the Antilles, those 
terribly destructive hurricanes, and cyclones. The direc- 
tion of the Mississippi valley is at right angles with the 
westerly belt of winds as defined by Coffin, but the winds 
of this belt in their course from the Pacific have to sur- 
mount the Rocky Mountains, and necessarily pass high 
over the valley, especially if it is already occupied by the 
surface currents either from the north or south. The 
winds from the polar basin would move close to the sur- 
face in consequence of their greater density, due to dry- 
ness and cold. If the rain-bearing winds from the south 
should meet those from the north with anything like equal 
force, there would necessarily be a conflict in opposing di- 
rections, and a mingling of the winds from opposite direc- 
tions, and some new direction would be given to the 
opposing currents. They could not return back upon 
themselves; they could not go far west, on account of 
the barrier opposed by the Rocky Mountain wall, and 
they could not be deflected readily to the southeast, 
because they would be met in that direction by the Alle- 31 
ghany range ? Now what way or direction is open to them ? 
They can go to the east or northeast. And in this con- 
flict of winds from north and south, the mass might, and 
probably would be elevated and carried up the eastern slope 
of the Rocky Mountains, until brought into the influence of 
the high westerly belt of winds, and then would be swept 
across the States north of the Alleghanies, as storm winds 
which would pass off the coast of New England, and follow 
the Gulf Stream, which is a river in the ocean, or turn 
further north, and pass down the St. Lawrence, another 
well defined river valley through which winds are disposed 
to blow. 
The winds which come over the Rocky Mountains have 
hitherto been considered the great weather breeders of the 
Mississippi Valley, and of the Northern States. If you 
examine the weather charts which accompany the monthly 
reviews issued by the Bureau of the Signal Service of the 
United States, at Washington, you will observe the track 
of storms there laid down, marked by a continuous black 
line ; so far as the track has been defined from actual obser- 
vations, this line commences in the Valley of the Missis- 
sippi generally, and extends eastward, but not unfrequently 
you will find a dotted line from over the top of the Rocky 
Mountains, which is made to connect with black lines 
representing the observed storm track; this dotted line 
represents the supposed course and source of the storm 
from the Pacific Ocean over the Rocky Mountains. The 
majority of the storm tracks commence in the valley, and 
take the directions indicated, but some come from low 
down the valley, and pass up in a direction from S. W. to 
N. E., along the western base of the Alleghanies, and 
some few commence in the Gulf, pass diagonally across 
the Peninsula of Florida, and up the Atlantic coast east of 
the Alleghany range. That the cold storms which tra- 
verse the plateau north of the Alleghanies come from the 32 
Pacific over the Rocky Mountains, is, I think, a mistaken 
supposition, for the temperature of the Pacific side of our 
Continent is much higher than on the Atlantic side in the 
same latitude, as is shown by the isothermal lines on all 
our weather charts. A cubic foot of the atmosphere from 
the Pacific side might be carried over the Rocky Moun- 
tains, and when on the summit it would be cold, because 
its bulk would have expanded to that of several cubic 
feet, and its heat being diffused through an increased bulk, 
it would be comparatively cold ; but after it had come over, 
and again been subjected to pressure in the valley, it would 
have lost little or none of its specific heat in its passage 
over, and cannot account for the cold experienced in these 
storms, nor for the amount of vapour condensed to pro- 
duce the rain which accompanies them. And if it is ad- 
mitted that the rain bearing winds from below bring the 
vapour up from the Gulf, why not admit that the cold dry 
winds from the northern end of the valley, is the source 
of the cold winds which does produce the condensation, 
and cold, also, which is experienced all over the plateau 
where the great lakes are situated, and over New England ? 
The explanation here advanced, as to the influence of the 
winds of this great valley in producing the northers which 
visit Texas, Mexico, and the Islands of the Antilles, and 
as the breeder of the storms in the Northern and Middle 
States, is, in my opinion, the true one in the main; there 
may be, and no doubt there are, many minor influences 
which I have not enumerated, which enter into and modify 
the phenomena witnessed in these storms. 
Prof. Espy used to consider the winds of the Pacific, 
coming over the Rocky Mountains, as the cause of the 
storms which swept across that northern plateau in which 
the upper lakes are situated ; but there was a peculiarity in 
his weather charts, and this was a line extending north and 
south, of considerable length, representing the storm trav- elling broadside eastward, moving majestically and slowly 
along ; but, had it come over the Rocky Mountains, would 
it have presented that kind of front ? The elevation of the 
Rocky Mountains are unequal; there are high peaks and 
comparatively low walls and gorges between them. Now 
if the winds were pressing with great force, they would 
rush through the gorges between the various peaks, not in 
those broad masses, but in narrower streaks, which would 
not present the broad front which he describes. But if the 
storms were produced by the winds of the valley meeting 
from the north and south, and were elevated until they 
were brought into the influence of the westerly belt of 
winds, the storm would then present the peculiar front 
elongated from north to south, which he has so correctly 
described. 
Now, in this connection, I will refer more particularly to 
the phenomena to which I have above merely alluded, as 
connected with the currents passing up and down the Mis- 
sissippi Valley. I mean the violent character of the 
circular or spiral storms in the Gulf and Caribbean Sea, 
called cyclones. The spiral movement of the wind in 
cyclones, in the Northern Hemisphere, is from the west to 
east, by south, and from east to west, by north. The 
cyclones in the Southern Hemisphere are in the opposite 
direction, that is, the spiral movement of the wind is effect- 
ed from west to east, by north, and from east to west, by 
south, and it has been explained as being the result of the 
meeting of the conflicting currents of the air, throwing 
them into spirals; and by some, that there is some cause 
in operation, peculiar to each hemisphere, which causes 
them to revolve in opposite directions in the respective 
hemispheres. Without attempting to go into a solution of 
the difficulties which attend the theories advanced, I only 
wish now to simply direct your attention to the conformation 
of the mountainous border of the Valley of the Mississippi, 34 
and of the Gulf of Mexico, and of the Caribbean Sea. In 
latitude 30°, where the 1080 of longitude crosses it, to be- 
low latitude io° N., where the 75th parallel of longitude 
crosses that, there is a regular curve in the mountain range 
turning eastward, as you go south, (and in this curve lies 
the Gulf of Mexico and the Caribbean Sea,) so as to give 
a spiral direction to the winds that are forced down the 
Valley of the Mississippi, and over these partially inclosed 
basins of water. Without insisting that these winds are 
the cause of the cyclones which are first formed over these 
bodies of water, the direction given to the winds, which are 
deflected from their northerly course by the curve of these 
mountains, would be a spiral corresponding with those 
which the cyclones of the Northern Hemisphere take, and 
if these winds do not create them, they are calculated to 
give force and intensity to those already formed. The 
diameter of these circular storms are at first comparatively 
small, but violent in force. After leaving the tropics, they 
are relieved from the lateral pressure of the N. E. trade 
winds, and have a free path before them, and soon come into 
the influence of the belt of westerly winds, bending in a 
graceful curve to the north and northeast, enlarging the di- 
ameter of the spirals, and consequently lose their violence 
as they advance, and usually following the course of the 
Gulf Stream. Meteors of lesser magnitude than the cyclone 
are often formed by the meeting of conflicting winds, and 
form whirlwinds on land, and waterspouts at sea. Some of 
these are destructive in their effects, and sometimes en- 
large into local cyclones, but these, we are not called 
upon to discuss in this connection. From what has been 
shown, it follows as a legitimate result of the operation 
of natural influences around us, that our position is a 
favorable one, and is out of the track of the storms which 
so frequently visit our neighbors of the North; and that 
we are also out of the track, and protected from, these ter- 35 
restrial influences which so violently disturb the equili- 
brium of the atmosphere south of us, nearer the tropics. 
The conflicting winds which are warring in the Valley of 
the Mississippi for the mastery, do not often overleap the 
summits of the Alleghanies to give us a taste of the quality 
of the storms which are carried eastward over the Northern 
plateau ; nor do those which, in the form of northers, visit- 
ing Texas, etc., reach us, but pass us by on the west, and 
expend their force upon the coasts and islands of the Gulf 
and Caribbean Sea, and those cyclones which are born in 
the sea of the Antilles, pass around us, seldom making us 
a visit, that is, to our disadvantage, but have a tendency to 
remove all noxious admixture in our atmosphere, if any 
such exist, and substituting an atmosphere that has been 
purified by the tempest, which has raged to the south and 
east of us, the direction from which our principal winds 
come, and towards which they blow, while these kind of 
storms pass on our borders. 
When treating of temperature, I neglected to notice a 
statement that I have seen in print relative to the extremes 
of temperature which had occurred in Florida. It has 
been stated that the thermometer here had been — 8°, or 
eight degrees below zero. Nothing of the kind, I will 
venture to say, has ever been recorded, nor has any tradi- 
tion ever handed down any such event. In the month of 
February, 1835, occurred, probably, the coldest weather 
which Florida has ever experienced since it has been 
known, by a white man at least; at the time alluded to, 
the thermometer was down to 8° above zero, and great 
damage was done to the orange and other trees at that 
time, and there were standing trees on the St. John’s 
River, and also, I think, at St. Augustine, which were a 
hundred years old at least, and they were killed with the 
rest, and this is an evidence that for a hundred years at least, 
such a frost had not occurred. I have once recorded the 36 
thermometer i6° above zero, and have three times record- 
ed it as low as 20° above zero in the last thirty-six years. 
It is not claimed for Florida that she is entirely exempt 
from all those influences which produce extremes of temper- 
ature north of us, but their effect upon Florida, in com- 
parison with other places north and west of us, is greatly 
modified here, so that we can claim to have a very equa- 
ble climate in comparison. 
And, now gentlemen, having occupied so much of your 
time, and having, I believe, discussed the various topics 
which constitute the factors of the climate, I am admon- 
ished of the propriety of bringing this address to a close, 
and will do so by giving a succinct summary of what we 
have found to be the results of the analyses of the mate- 
rial which has been above elaborated. In regard to Tem- 
perature, that has been found excessive in neither extreme 
throughout the entire year, but quite equable. Atmos- 
pheric disturbances of a serious character are not as fre- 
quent here as either north or south of us, for our equable 
temperature has been shown to have an astronomical cause, 
which gives us less heat in summer, and less cold in winter 
than in northern latitudes. And the regularity of barom- 
etrical pressure in its relation to temperature, shows that 
there is a remarkable and equable relation existing between 
the two. The humidity of the atmosphere has been shown 
to exist to such an extent as to prevent those extreme 
diurnal variations of temperature which are inimical to both 
comfort and health, and on the other hand, the absolute 
amount of water in the atmosphere is too small to render 
it objectionable to even delicate lungs. The fall of rain 
occurs principally in showers during the summer and 
autumn, when the agricultural interests most require it. 
The winter is the dryest season and the spring next, in 
the latter part of which it is sometimes quite dry. 
The showers which occur in summer are of short dura- 37 
tion, and come on with considerable regularity, making the 
summer more pleasant and the air pure and cool. The at- 
mosphere, as has been before remarked, is comparatively 
calm, and what winds we do have are seldom of a violent 
or destructive character. 
We have on an average about twenty clear days in the 
month, or about two hundred and forty in the year. The 
excessively cloudy weather which has characterized the 
January of this year, 1875, is a marked exception to all 
former years since my residence in Florida, and has most 
probably resulted from some general disturbance of the 
atmosphere, which has at the North produced such intense 
cold as will probably be remembered hereafter as one of 
those cold winters which,at long intervals, will visit a coun- 
try, but we should after all consider this character of weather 
as a blessing in disguise, as not the tenderest vegetable which 
has been exposed to all weathers has been injured by frost 
this winter. The electric tension of the atmosphere has been 
considered one of the elements of climate, but into this 
subject I have made no investigation, nor am I aware that 
any special attention has been paid to it. I will not, there- 
fore, make any pretence of showing what, if any, influence 
it may have on our climate. This is one of those quiescent 
forces of the earth which are roused into activity by the 
action of the sun’s rays. I have not deemed its influence 
sufficiently important to make it the subject of special 
study in connection with meteorology. I have kept a 
record of thunder showers, and from that I find that most 
of them have occurred in the spring, summer and autumnal 
months, and very few in the winter. Sometimes we have 
cloud lightning without audible thunder, on the horizon, 
in the evening. We have occasionally had some beautiful 
exhibitions of the Aurora Borealis, some of which might 
be termed gorgeous. Meteors and shooting stars are not 
unfrequently observed, and some other meteoric phe- 38 
nomena have been observed, which it is unnecessary to 
allude to here. As the admixture of foreign substances in 
the atmosphere is referred to in Humbolt’s definition of 
climate, I would remark that probably there may be some 
admixture of saline matter near the sea shore, as some 
vegetables will not grow there, which do in the interior. 
Carbonic acid gas probably exists in a moderate amount. 
As the generation of ozone is accomplished in the labor- 
atory by the transmission of electricity through oxygen, 
its formation is probably effected to a greater or less ex- 
tent during our summer thunder showers; but I have no 
facts to demonstrate its existence, or its effect upon health. 
The subject of miasmata I have spoken of already, and we 
have nothing in Florida to render it the cause of disease 
more than in any country north of us, where new soil is 
turned up to the air and sun. The heat which we have, does 
not seem to generate any thing of the kind here, more than 
elsewhere. Florida is, happily, free from many of the dis- 
eases which are prevalent elsewhere. The only records 
to which we have hitherto had access, are those of the army, 
when troops have been stationed in different portions of 
the State, some of which might be suspected of being 
sickly ; but these present the gratifying result that Florida 
is one of the healthiest States in the Union. I trust that 
under the auspices of this association, a systematic effort 
will be made to secure reliable information as to the vital 
statistics of the State, and the character of the hygienic 
condition of the residents generally and locally. 
I have now performed the duty assigned me. I have 
analyzed the materials which I had collected, and which I 
believe on the whole to be sufficiently reliable from which 
to derive a fair result, and if the results of their analysis 
shall have the effect of imparting a more correct know- 
ledge of the climate of Florida, as it really exists, the 
labour, which has been required to arrive at these results, 
will be amply repaid. S. W Me cell's Table, Showing the Sun's Diurnal Intensity 
at every io Degrees of Latitude in the Northern Hem- 
isphere. 
1 LAT. 
1 ° 
LAT. 
IO° 
LAT. 
20° 
LAT. 
3°° 
LAT. 
4°° 
LAT. 
5°° 
LAT. 
6o° 
LAT. 
70° 
LAT. 
8o° 
LAT. 
9O0 
January 
I 
77-1 
67.2 
33-8 
42 8 
30.1 
16 5 
5-1 
<< 
16 
78 I 
68.9 
58.2 
45 8 
32.7 
J9-3 
7.2. 
u 
31 
79.6 
71.7 
61.9 
49-7 
38-6 
2<;.0 
11 9 
i-4 
February 
I c 
81.0 
74-7 
66.6 
55.6 
45-1 
3*-9 
I9.O 
64 
March 
2 
81.6 
78.0 
7i-3 
62.9 
52 7 
41-1 
27-9 
H 5 
2.1 
<< 
*7 
82.0 
80.2 
76.0 
69.6 
6l. I 
5°.2 
37.1 
25 5 
11.6 
April 
I 
80 8 
81.4 
79-5 
75 6 
68.9 
60.2 
49-9 
38.O 
25.6 
2O.5 
“ 
l6 
79 0 
81.7 
82.0 
79 5 
75-i 
68.6 
6l. I 
S1 4 
44 0 44- 6 
May 
I 
76.9 
81.s 
83 7 
83 6 
80.8 
77.1 
7°. 9 
64 6 
64.3 
63.3 
16 
74-7 
80.8 
84.7 
86.7 
85.7 
83.3 
79-7 
76 8 
80.3 
81.5 
U 
31 
73.0 
80.1 
85.1 
87.8 
88.9 
87.8 
8.5-7 
86.8 
91.0 
92-4 
June 
lS 
72.0 
79 6 
83.2 
88.4 
90. I 
89.9 
88.8 
91.7 96 1 
97.6 
July 
I 
72.0 
79-5 
85.0 
88.3 
9°. 4 
89.5 
88.4 
90.8 93-1 
96.6 
u 
16 
73.0 
79.8 
84.7 
87.5 
87.6 
86 5 
84.1 
84 3 
88.3 
89.7 
a 
31 
74-7 
80.4 
83 9 
85.1 
84.3 
81.6 
77-3 
73 4 
76.2 
77-4 
August 
!S 
76.7 
80 8 
82.7 
82.4 
79.8 
74-7 
68.2 
60.9 
59-2 
60.1 
<< 
30 
78.5 
80.7 
80.6 
77-7 
72. I 
65.5 
57-3 
47-7 
38.8 
38.9 
Sept’ber 
14 
79.8 
79.8 
77-5 
72 8 
65.9 
58.8 
46.9 
34-5 
21.9 
14-7 
n 
29 
80.5 
78.4 
73 8 
67.0 
57.8 
47.0 
36 2 
22.5 
9 0 
October 
H 
80.7 
76.4 
69.7 
61.0 
$0.2 
38.2 
25-7 
12.6 
1.0 
u 
29 
79-9 
73-5 
650 
54.6 
42-5 
JO. I 
17-5 
5-2 
Nov’ber 
*3 
78.8 
70.7 
60.8 
49.8 
37-i 
2 3 8 
I I .O 
0.9 
U 
28 
77-5 
68.3 
57-3 
45 3 
31 • 81 
18.9 
6.8 
Dec’ber 
J3 
76.9 
66.9 
55-4 
43.0 
30.3! 
16.3 
4-9 
By the above table, the amount of sun’s rays which fall on the day given, is 
shown on the different degrees of Latitude. The table has been computed for 
intervals of fifteen days, and expresses the results in units of intensity. The choice 
of a unit being entirely arbitrary; the intensity of a day on the Equator, at the 
time of the vernal Equinox, is here assumed to be 81.5, and other values are 
expressed in that proportion. In the last three columns for the frigid zone, the 
braces ,—* include values for the days, when the sun shines through the whole 
twenty-four hours; the blank spaces indicate periods of constant polar night. MEAN TEMPERATURE OF 
FLORIDA. 
RAIN-FALL IN FLORIDA 
Latitude. 
Longitude. 
Spring. 
Summer. 
Autumn. 
j Winter. 
Year. 
Spring—inches. 
Summer—inches. 
Autumn—inches. 
Winter—inches. 
Year— inches. 
Observation 
of Therm’r. 
Observation 
of Rain-fall. 
No. of Year 
Observed. 
Parts of Yr. 
Observed. 
No. of Year 
Observed. 
Parts of Yr. 
Observed. 
& part of 
& part of 
1. Key Wost 
24.32 
81.48 
75.79 
82.51 
78.23 
69.58 
76.51 
8.34 
16.51 
15.35 
7.37 
47.65 
14 
2 years. 
5 
5 
& part of 
25.55 
80.20 
74.66 
81.50 
76.27 
66.58 
74.75 
(13 26 
18.89 
17.11 
9.78 
59.04) (*) 
1 
9 years. 
3 
5 months 
& part of 
26.38 
82.00 
75.89 
82.41 
77.00 
68.36 
75 04 
11.07 
30.91 
11.96 
8.33 
62.26 
4 
4 
2 
& part of 
27.30 
80.20 
73.44 
81.31 
74.80 
63.27 
73.20 
11.13 
26.25 
16.84 
8.76 
62.98 
4 
2 
3 
& part of 
28.00 
82.28 
72.06 
80.20 
73.08 
62.85 
71.9 
8.57 
28.24 
10.63 
8.04 
55.41 
25 
11 
5 
& part of 
28 01 
82.00 
71.87 
79.34 
73.82 
60.90 
71.48 
8.76 
20.68 
69.5 
3.87 
40.22 
2 
2 
2 
& part of 
28.54 
81.02 
71.80 
79.14 
62.43 
63.22 
69.17 
( 3.50 
14.45) (*) 
1 
9 months 
( 5.83 
19.84 
11.73 
7.53 
44.93) (*) 
7.10 
8. Cedar Keys 
29.07 
83.03 
70.02 
79.07 
71.04 
58.22 
69.60 
4.10 
22.35 
11.94 
10.11 
48.50 
2 
7 months 
2 
1 
29 10 
82 10 
70.22 
80.22 
70.69 
58.41 
70.04 
6 
30 miles 
N.E.of 
in urA..Annnnnn 
70 28 
78 87 
69.29 
57 45 
68.97 
2 
29.34 
81.48 
70.62 
83.57 
70.20 
57.18 
69.64 
12.49 
21.49 
9.71 
4.99 
48.68 
6 
3 
12. Micanopy 
29.30 
82.28 
72.02 
79.55 
69.80 
59.98 
70.09 
( 9.29 
24.48 
12.47 
7.17 
54 36) (*) 
4 
3 months 
1 
7 months 
29.35 
83.00 
71.11 
80.96 
71.07 
70.20 
2 
(10.53 
17.38 
9.09 
6.16 
43.16) (*) 
g 
& part of 
29.48 
81.30 
68.54 
80.27 
71.73 
58.08 
69.61 
5.90 
10.54 
9.46 
5.80 
31.80 
20 
1 
4 
29.48 
81.45 
70.08 
80.61 
72.23 
54.90 
69.46 
1 
& part of 
30.18 
87.27 
68.59 
81.57 
69.86 
54.92 
68.74 
12.86 
18.69 
13.71 
11.72 
56.98 
17 
3 
8 
& part of 
30 20 
81.25 
70.06 
81.82 
70.36 
56.33 
69.38 
9.19 
20.50 
12.98 
7.60 
50.29 
27 
16 
3 years. 
& part of 
30 96 
84 00 
71.52 
79.39 
68.36 
56.91 
69.04 
1 
2 years. 
30 30 
85 30 
7.62 
16.64 
9.45 
10.36 
44.07 
1 
7 months 
Lake City 
30.12 
82.37 
(69.0 
81.3 
71.6 
58.3 
70.0 ) (*) 
(16.34 
26.15 
20.88 
15.04 
78 38) (*) 
1 
1858 
2 
8 months 
Gainsville 
(29.35 
82.26 
(67.32 
78.42 
71.12 
59.59 
69.11) (*) 
( 8.33 
20.18 
7.94 
8.46 
44.91) (*) 
1 
1858 
4 
7 months 
26 30 
81 30 
( 9 34 
28.06 
6.99 
10.71 
55.30) (*) 
2 
o months 
30 90 
87 18 
(14.84 
20.70 
14.61 
13.69 
63.78) (*) 
3 
8 months 
Manatee 
27.27 
82.10 
(72.6 
83.8 
76.7 
65.3 
74.6 ) 
(12.90 
23.10 
5.60 
9.08 
50.68) (*) 
1 
1869 
Sums 
1,289.13 
1,449.25 
1,290.00 
1,080.81 
10.02 
232.81 
1,129.01 
86 95 
Means 
71.62 
80.51 
71.66 
60.04 
70.95 
9.09 
21.16 
12.64 
7.90 
50.97 
(*) Those in brackets do not enter into the Sums or Means, as the returns are not reliable, and missing months were interpolated, and these interpolations have, at some 
of the stations, been so far from the actual measurement, as to materially change the result of the year, and those have been added siDoe the tables were first constructed, and for 
fuller information. The annual Rain-fall of Florida, as given by the Smithsonian Tables and Results, is 49.49 inches.