al interest are the electrical connections on the observer's
table itself. A diagrammatic representation of the observer's table with
its connections is shown in fig. 17. The heavy black outline gives in a
general way the outline of the table proper and thus shows a
diagrammatic distribution of the parts. The first of the electrical
measurements necessary during experiments is that of the
thermo-electric effect of the thermal junction systems installed on the
calorimeters. To aid in indicating what parts of the zinc wall need
cooling or heating, the thermal junction systems are, as has already
been described, separated into four sections on the chair calorimeter
and three sections on the bed calorimeter; in the first calorimeter, the
top, front, rear, and bottom; in the bed calorimeter, the top, sides,
and bottom.

CONNECTIONS TO THERMAL-JUNCTION SYSTEMS.

Since heretofore it has been deemed unwise to attempt to use both
calorimeters at the same time, the electrical connections are so made
that, by means of electrical switches, either calorimeter can be
connected to the apparatus on the table.

The thermal-junction measurements are made by a semicircular switch
S_{7}. The various points, I, II, III, IV, etc., are connected with the
different thermal-junction systems. Thus, by following the wiring
diagram, it can be seen that the connections with I run to the different
binding-posts of the switch S_{10}, which as a matter of fact is placed
beneath the table. This switch S_{10} has three rows of binding-posts.
The center row connects directly with the apparatus on the observer's
table, the outer rows connect with either the chair calorimeter or the
bed calorimeter. The points marked _a_, _b_, _d_, _e_, _f_, etc.,
connect with the bed calorimeter and A, B, D, etc., connect with the
chair calorimeter. Thus, by connecting the points _g_ and _i_ with the
two binding-posts opposite them on the switch S_{10}, it can be seen
that this connection leads directly to the point I on the switch S_{7},
and as a matter of fact this gives direct connection with the
galvanometer through the key on S_{7}, thus connecting the
thermal-junction system on one section of the bed calorimeter between
_g_ and _i_ directly with the galvanometer. Similar connections from the
other points can readily be followed from the diagram. The points on the
switch S_{7} indicated as I, II, III, IV, correspond respectively to the
thermal-junction systems o