plete,
including all previous figures.]

The whole apparatus is permanently and substantially installed on the
north wall of the calorimeter laboratory. A photograph showing the
various parts and their installation is given in fig. 23. On the top
shelf is seen the galvanometer and on the lower shelf the recorder with
its glass door in front and the coordinate paper dropping into the box
below. The curve drawn on the coordinate paper is clearly shown. Above
the recorder are the resistance-boxes, three in number, the lower one at
the left being the resistance S_{1}, the upper one at the left being the
resistance S', and the upper one at the right being the resistance
Z_{1}. Immediately above the resistance-box Z_{1} is shown the plug
resistance-box which controls on the one hand the resistance _r_ and on
the other hand the resistance S, both of which are substantially altered
when changing the apparatus to register from the 0 deg. to 4 deg. scale to
the 0 deg. to 8 deg. scale. A detailed wiring diagram is given in fig. 24.

TEMPERATURE CONTROL OF THE INGOING AIR.

[Illustration: FIG. 25.--Section of calorimeter walls and part of
ventilating air-circuit, showing part of pipes for ingoing air and
outgoing air. On the ingoing air-pipe at the right is the lamp for
heating the ingoing air. Just above it, H is the quick-throw valve for
shutting off the tension equalizer IJ. I is the copper portion of the
tension equalizer, while J is the rubber diaphragm; K, the pet-cock for
admitting oxygen; F, E, G, the lead pipe conducting the cold water for
the ingoing air; and C, the hair-felt insulation. N, N are brass ferules
soldered into the copper and zinc walls through which air-pipes pass; M,
a rubber stopper for insulating the air-pipe from the calorimeter; O,
the thermal junctions for indicating differences of temperature of
ingoing and outgoing air and U, the connection to the outside; QQ, exits
for the air-pipes from the box in which thermal junctions are placed; P,
the dividing plate separating the ingoing and outgoing air; R, the
section of piping conducting the air inside the calorimeter; S, a
section of piping through which the air passes from the calorimeter; A,
a section of the copper wall; Y, a bolt fastening the copper wall to the
2-1/2 inch angle W; B, a portion of zinc wall; C, hair-felt lining of
asbestos wall D; T-J, a thermal junction in the walls.]

In passing the current of air through the calorimeter, temper