TECHNIQUE FOR METABOLISM DURING REST. 



97 



from timber 4 inches square; this framework had a width of approxi- 

 mately 13 feet 3| inches and a length of 17 feet 9^ inches. To this base 

 were fastened the several uprights which were covered with a sheathing 

 of f-inch matched lumber. The framework on the floor was then lined 

 with galvanized iron, which extended up 10 inches on the wooden walls 

 of the chamber, for it was believed that the greatest stress and wear 

 would be borne by these parts. The rest of the inner metal lining was 

 made from tinned sheet iron. The inner metal lining of the chamber 

 has therefore a length of 17 feet, a width of 12| feet, and a height of 7^ 

 feet. The outside of the chamber was finished with |-inch "compo 

 board," which was painted. Between the compo board and the inner 

 wooden wall is an air-space of 4 inches. 



il & 



3ir 



ii r\ 



m 



fWk 



m 



Fig. 7. — Cross-section of group respiration chamber from west to east. 



a, Inner wooden floor; b, opening for ingoing air; ci, C2, and C3, ^-inch suspension-rods; d, step- 

 ladder; /, trap-door; g, water-seal trough; h, brine coils; k, rotary air-impeller; m, Bunsen 

 burner for heating ingoing air; n, butterfly valve. 



To prevent excessive wear of the galvanized iron floor, it was nec- 

 essary to install an inner wooden floor (a in figs. 6 and 7), which was 

 made of |-inch maple flooring, resting upon 2 by 4 inch wooden 

 stringers, laid on edge. This floor was substantially made and well 

 smoothed to secure a rigid base upon which groups of individuals could 

 walk with freedom or perform severe muscular exercise. The original 

 intention was to have the floor as nearly as possible air-tight, so as to 

 consider as the flexible or movable portion of air inside the chamber only 

 that above the floor. For this purpose a copper flashing was soldered 

 to the bottom of the metal wall, turned in over the top of the maple 

 flooring, securely tacked to the floor and filled in with shellac. 



