THE CALORIMETER. 15 



for weighing the man, the series of small channels set on edge upon which 

 the asbestos floor is laid, and the upright row of channel ribs are all clearly 

 shown. 



A photograph taken subsequently, showing the inner copper lining in 

 position, is given in fig. 11. 



The floor of the chamber is supported by 7 pieces of 2^-inch channel 

 (N, 1ST, N, fig. 8), laid on top and bolted to the two 3-inch channels (M, 

 fig. 8). On top of these is placed a sheet of so-called asbestos lumber (J', 

 fig. 8) 9.5 millimeters thick, cut to fit exactly the bottom of the chamber. 

 Upright 2^-inch channels (H, fig. 8) are bolted to the two outside channels 

 on the bottom and to the ends of three of the long channels between in 

 such a manner as to form the skeleton of the walls. The upper ends of 

 these channels are fastened together by pieces of piping (P, P, P, fig. 8) 

 with lock-nuts on either side, thus holding the whole framework in position. 



The I-beams and channels used to tie the four upright channels at the top 

 form a substantial platform upon which is mounted a large balance (fig. 9). 

 This platform is anchored to the ceiling at four points by tie rods and turn- 

 buckles, shown in fig. 1. The whole apparatus, therefore, is extremely rigid 

 and the balance swings freely. 



The top of the chamber is somewhat restricted near the edges (fig. 8) 

 and two lengths of 2^-inch channel support the sides of the opening through 

 which the subject enters at the top (fig. 7). 



Both the front and back lower channels upon which the bottom rests are 

 extended so as to provide for supports for the outer walls of asbestos wood, 

 which serve to insulate the calorimeter. Between the channels beneath the 

 calorimeter floor and the 3-inch channels is placed a sheet of zinc which 

 forms the outer bottom metallic wall of the chamber. 



In order to prevent conduction of heat through the structural steel all 

 contact between the inner copper wall and the steel is avoided by having 

 strips of asbestos lumber placed between the steel and copper. These are 

 shown as J in fig. 8 and fig. 12. A sheet of asbestos lumber beneath the 

 copper bottom likewise serves this purpose and also serves to give a solid 

 foundation for the floor. The supporting channels are placed near enough 

 together to reinforce fully the sheet of asbestos lumber and enable it to sup- 

 port solidly the weight of the man. The extra strain on the floor due to 

 tilting back a chair and thus throwing all the weight on two points was taken 

 into consideration in planning the asbestos and the reinforcement by the 

 steel channels. The whole forms a very satisfactory flooring. 



Wall construction and insulation. — The inner wall of the chamber con- 

 sists of copper, preferably tinned on both sides, thus aiding in soldering, and 

 the tinned inner surface makes the chamber somewhat lighter. Extra large 

 sheets are obtained from the mill, thus reducing to a minimum the number of 



