the position of complete muscular rest
introduced by Johansson and his associates. While the body positions
maintained by Zuntz and Johansson may be the best positions for
experiments of short duration, it was found, as a result of a large
number of experiments, that subjects could be more comfortable and quiet
for periods of from 6 to 8 hours by sitting, somewhat inclined, in a
comfortable arm-chair, provided with a foot-rest. With this in mind the
first calorimeter was constructed so as to hold an arm-chair with a
foot-rest so adjusted that the air-space between the body of the subject
and the walls of the chamber could be cut down to the minimum and thus
increase the accuracy of the determination of oxygen. That the volume
has been very materially reduced may be seen from the fact that the
total volume of the first calorimeter to be described is less than 1,400
liters, or about one-third that of the Middletown apparatus.

GENERAL CONSTRUCTION.

A horizontal cross-section of the apparatus is shown in fig. 7, and a
vertical cross-section facing the front is given in fig. 8. Other
details of structural steel are seen in fig. 9.

In constructing the new chambers, the earlier wood construction, with
its tendency to warp and its general non-rigidity, was avoided by the
use of structural steel, and hence in this calorimeter no use whatever
is made of wood other than the wood of the chair.

To avoid temperature fluctuations due to possible local stratification
of the air in the laboratory, the calorimeter is constructed so as to be
practically suspended in the air, there being a large air-space of some
76 centimeters between the lowest point of the calorimeter and the
floor, and the top of the calorimeter is some 212 centimeters below the
ceiling of the room. Four upright structural-steel channels (4-inch)
were bolted through the floor, so as to secure great rigidity, and were
tied together at the top with structural steel. As a solid base for the
calorimeter chamber two 3-inch channels were placed parallel to each
other 70 centimeters from the floor, joined to these uprights. Upon
these two 3-inch channels the calorimeter proper was constructed. The
steel used for the most part in the skeleton of the apparatus is
standard 2-1/2-inch channel. This steel frame and its support are shown
in fig. 10, before any of the copper lining was put into position. The
main 4-inch channels upon which the calorimeter is supported, the