ERRORS IN VENTILATION.—NO. 2. 
By William Henry Thayer, m.D., Brooklyn, N. Y. 
I HAVE received many communications from different parts 
of the country, almost all expressing approval of the state- 
ments in the paper on “ Errors in Ventilation” in the April 
number of The Sanitarian, and gratification that public at- 
tention was called to the subject. 
Only three of my correspondents are inclined, for various 
reasons, to favor the withdrawal of used-up air from the lower 
part of the room. One of them writes : ”... In winter the 
air supplied to the school-room must be warm. Heated air 
diffuses slowly, rising immediately to the ceiling when intro- 
duced into the room. If your exhausts are at the ceiling, this 
volume of warm fresh air will be lost, and the coldest air will 
remain in the room. Under such conditions, how will you 
warm the room ?” 
To him I replied : “ I have never discovered in any rooms 
that had the escape for foul air in the upper part of the room 
any of the difficulty you suggest. If the inlets for warm air 
in or near the floor are large enough to admit a great volume 
at a temperature not many degrees above blood-heat—as they 
should be —the room is thoroughly and equally warmed. The 
hall of the Brooklyn Institute, which I gave as a good exam- 
ple, was faultless in its atmosphere in regard to temperature 
and purity. The inlets and outlets should be properly pro- 
portioned in size, and the results will be agreeable. If all the 
air admitted to the room is warmed, there will be no cold 
residuum for the lower part of it.” 
To another correspondent, who, agreeing with the princi- 
ples I had advocated, still thought that public rooms might 
be successfully ventilated by outlets near the floor, I wrote : 
“ I think we should agree about the necessities in the ventila- 
tion of buildings—that there must be an ample supply of pure 
air from the outside, forced or made sure, and a free passage 2 
Errors in Ventilation. 
outward for the foul air. If the outward passage is in the 
ceiling, the foul air will not need artificial aid for its escape. If 
the place of exit is near the floor, a motive power will be needed 
to carry it off ; and the room may be perfectly ventilated in 
that way, if the motive power is of adequate force, and the sup- 
ply of pure air admitted in sufficient quantity. But I do not 
understand the object of carrying off the foul air at the level 
of the floor. What is gained over ventilation through the 
ceiling ? It cannot be claimed that you save more heat ; for 
if the outward current is strong enough to purify the room, 
there will be as great a discharge of warm air at the lower 
openings, as if it passed out through the ceiling without artifi- 
cial aid. 
“ I think the erroneous belief that the air which is surcharged 
with carbon dioxide falls to the floor, and produces an excess 
of the dioxide there, still lingers in the minds of those who 
propose to ventilate from the lower part of the room.” 
The third correspondent, an eminent sanitarian, writes that 
he prefers ventilation near the floor, to insure the carrying off 
of disease germs. He evidently believes that the germs of 
specific diseases settle to the floor by their weight. To allow 
these microscopic objects, almost imponderable, to be de- 
posited on the floor or in the lower part of the room, is to 
suppose the entire absence of all atmospheric currents—to 
imagine rooms totally devoid of all opportunities for ventila- 
tion. With proper inlets and outlets, all germs of disease 
would be thoroughly removed, and have no opportunity to 
settle to the floor ; and, removed into the pure outer air, they 
do not multiply, but die. Oxygen, as all physicians know, is 
a perfect disinfectant. 
A personal experience in 1863, in Washington, D. C., is 
strikingly illustrative of the complete removal and disinfection 
of the germs of a specific disease by free ventilation. My 
regimental hospital in Gales’s Woods was composed of three 
hospital tents, pitched together so as to make one tent 48 feet 
in length, and accommodating 24 patients. It was raised 
upon a skeleton frame, and with a board floor 18 inches above 
the ground. During the summer the canvas sides were rolled 
up completely, and never lowered, so that the tent was en- 
tirely open all around. In June a patient with diphtheria was Errors in Ventilation. 
3 
brought in, and from that time till winter there was no time 
when there was not at least one case of this disease in the 
hospital—there being twelve cases there during five months. 
The beds were all occupied with sick men, but no one in the 
hospital contracted the disease. In November, the onset of 
cold weather obliged us to let down the sides of the tent. In 
the course of the month the disease attacked a number of the 
patients in the hospital, making it necessary to remove to gen- 
eral hospital all those who had already escaped the infection, 
and admit no more. But for five months, in out-door air, the 
diphtheric and other patients had lain in contiguous beds, not 
two feet apart, without a single case of infection within the 
tent. This complete ventilation proved a perfect disinfectant 
—as has been shown in many other instances, but never more 
convincingly than in this case. 
Since the publication of the April number of The Sanita- 
rian, I have examined the warming and ventilating arrange- 
ments in St. Ann’s Church, in Brooklyn, of whose atmosphere 
Dr. Bartley made an analysis. I went there just before a fore- 
noon service, when the house might be expected to have the 
best atmosphere. The air was offensive to the sense of smell, 
as if it had been at the close of service, in a crowded house 
without ventilation. 
On investigation, it appeared that no air was admitted to 
the building, except what might enter while the doors were 
open. I was informed that there were flues for admitting 
fresh air at the east end. I looked for the openings of these 
fresh-air flues on the outside of the church, and found four 
openings near the ground, each about twelve inches square ; 
but they were all carefully closed, by Canton flannel nailed over 
them ! I discovered that the flues from these openings ex- 
tended to the risers of the chancel steps, with openings there ; 
so that, before they were closed, strong currents of cold air 
were doubtless discharged in the faces of the occupants of the 
front pews. The air was evidently shut off as a nuisance, by 
covering the openings on the outside. 
The excessive foulness of the air was thus accounted for ; 
the outlet flues carry little off, for there is no fresh air to take 
its place, except what enters while the church-doors are open. 
We cannot draw air out of a room if we do not provide an 4 
Errors in Yentilation. 
inlet for a ne supply. I went into the tower—which, by 
the way, is heated by steam pipes and not by gas, as stated 
incorrectly in my April paper—and found no current flowing 
out of the great ventilating pipe that opens from the church. 
How could there be an outward current, if no air entered the 
building from the outside ? It is not strange that its atmos- 
phere, as analyzed by Dr. Bartley, was fouler than that of any 
of the numerous halls examined by Dr. R. C. Stiles in 1869. 
The strange and sad part of it, is, that a congregation could 
endure this state of things for twenty years, without complaint 
or investigation. One cannot easily overestimate the crimi- 
nality of such arrangements, inevitably undermining the 
health of so many people. 
[.Reprinted from The Sanitarian for July, 1892.]