[Illustration: FIG. 17.--Diagram of wiring of observer's table. W_{1}, W_{2}, Wheatstone bridges for resistance thermometers; K_{1}, K_{2}, double contact keys for controlling Wheatstone circuits; S_{1}, S_{2}, S_{3}, double-pole double-throw switches for changing from chair to bed calorimeter; S_{4}, double-pole double-throw switch for changing from wall to air thermometers; G, galvanometer; R_{2}, rheostat. 1, 2, 3, 4, 5, wires connecting with resistance-coils A B D E F and _a b d e f_; S_{2}, 6-point switch for connecting thermal-junction circuits of either bed or chair calorimeter with galvanometer; S_{10}, 10-point double-throw switch for changing heating circuits and thermal-junction circuits to either chair or bed calorimeter; R_{1}, rheostat for controlling electric heaters in ingoing water in calorimeters; S_{8}, double-pole single-throw switch for connecting 110-v. current with connections on table; S_{9}, double-pole single-throw switch for connecting R_{1} with bed calorimeter.] Of special 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.