ZOOLOGICAL GARDENS—LOISEL. 439 
nied by Mr. Biittikofer, who with the greatest kindness furnished me 
with all the information that I wished. There were at that time 
150 monkeys in the interior cages and the morning cleaning up was 
not yet finished; still there was no bad odor and the air seemed as 
agreeable as that of a conservatory. 
The double problem that had to be solved in constructing this 
house was, first, tp obtain in all the cages an equable and constant 
temperature of at least 20° even during the greatest cold; second, to 
establish an ample ventilation, without drafts, so as to reduce to a 
minimum the disagreeable odor which I have found in various degrees 
in most of the monkey houses that I have visited. 
In order to realize these desiderata, Mr. Biittikofer resolved to 
seek inspiration, if not to copy exactly the systems of heating and 
ventilation used in the new monkey house of the zoological garden 
at New York. The furnace room and store of coal are placed in a 
large cellar under the eastern extremity of the building. The water, 
brought nearly to the boiling point, enters a system of tubes 300 
meters long, is carried throughout the entire building and returns 
cooled to the furnace. Four large hot-water pipes are under the 
cages, two other smaller ones run along the exterior walls in the 
upper part of the cages, so that the air cooled by the exterior walls is 
sufficiently reheated and the monkeys have there quite warm places, 
where they like to remain. 
The ventilation is intimately connected with the heating. The 
cold air enters freely into two large conduits that run under the 
floors of the cages throughout their length close by the hot-water 
pipes, escapes by orifices in the upper part of these conduits, becomes 
heated by contact with the hot-water pipes, and warms the floor of 
the cages; then passes into the central hall through registers placed 
in front of the cages. From the hall a large part of the air enters 
the cages through the grills, then rises toward openings in the roof 
of each cage near the exterior wall, by which it passes into a conduit 
that communicates with two evacuation pipes. In this way the air 
that has been used and vitiated in the cages is removed from the 
building and can not return to the public hall. This outlet for 
vitiated air is favored by the inclined, interior roof of each cage; 
this roof, indeed, heated on both surfaces does not cool the vitiated 
air and prevents it from falling back into the cage. A simple system 
of valves placed at the inlet for cold air and the outlet for heated 
air enables one to regulate the currents. Besides, the ventilating 
chimneys are so made that in case this automatic ventilation should 
prove to be insufficient electric ventilators could easily be installed. 
The fact that most of the monkeys inhabit moist tropical forests, 
and therefore should have air with a certain degree of humidity, has 
not been forgotten. 'To accomplish this there have been placed in the 
41780—08——32 
