weighing oxygen cylinders. On the wall,
in the rear, is the recording apparatus for electric resistance
thermometers in the water-circuit, a detail of which is shown in fig.
23. In the foreground in the center is seen the observer's table; at the
right of this is shown the table for the absorption system, and at the
left the chair calorimeter with the balance for weighing subjects above
it. The mercury-vapor light, which is used to illuminate the room, is
immediately above the balance for weighing absorbers.

[Illustration: FIG. 6.--Plan of heating and ventilating calorimeter
laboratory, showing general plan of circulation of the special cooling
system and the position of the thermostats and radiators which they
control. The two small diagrams are cross-sections of brine and heating
coils.]

The bed calorimeter and the absorbing-system table are better shown in
fig. 4, a general view of the laboratory taken near the temperature
recorder. In the immediate foreground is the table for the absorption
system, and back of it are the observer's table and chair calorimeter.
At the right, the bed calorimeter with the front removed and the rubber
hose connections as carried from the absorber table to the bed
calorimeter are shown. At the extreme left is the balance for weighing
the absorbers. Above the chair calorimeter can be seen the balance for
weighing the subject, and at its right the galvanometer suspended from
the ceiling.

The west side of the laboratory at the moment of writing contains the
larger proportion of the apparatus. On the east side there exist only
the balance for weighing oxygen cylinders and an unfinished[4] large
calorimeter, which will be used for experiments of long duration. A view
taken near the front end of the bed calorimeter is shown in fig. 5. At
the right, the structural skeleton of the large calorimeter is clearly
shown. Some of the copper sections to be used in constructing the lining
of the calorimeter can be seen against the wall in the rear.

At the left the balance for weighing the oxygen cylinders is shown with
its counterpoise. A reserve oxygen cylinder is standing immediately in
front of it. A large calorimeter modeled somewhat after the plan of
Sonden and Tigerstedt's apparatus in Stockholm and Helsingfors is
planned to be built immediately back of the balance for weighing oxygen
cylinders.

HEATING AND VENTILATING.

Of special interest in connection with this calorimeter laborat