Improved Respiration Calorimeter 333 



the copper wall. A spindle is pushed through the sleeve and into the 

 thimble until the junctions projecting from its inner end are very close to 

 the bottom of the thimble, actual contact being prevented by the adjust- 

 ment of a small screw in the end of the spindle. A change in the tem- 

 perature of the copper wall immediately affects the temperature of the 

 thimble attached to it, and consequently that of the junctions within 

 the thimble. The junctions in the recess at the other end of the spindle 

 are within the sleeve attached to the zinc wall, and any change in the 

 temperature of the zinc wall affects the sleeve and, hence, the tempera- 

 ture of the junctions within it. Since both the sleeve and the thimble 

 are short, neither affects the temperature of the wire in the elements any 

 considerable distance from the junctions. The sleeve, however, projects 

 slightly either side of the zinc wall, so that it will surround the junctions, 

 even when they might come inside or outside the plane of the zinc, be- 

 cause of inequalities of distance between the two metal walls. 



A short section of the spindle, between the recess and one end, projects 

 from the outer end of the sleeve in the zinc wall and provides a firm stay 

 for the terminals of the elements. 



There are 95 such thermoelements distributed in the walls of the 

 chamber. If they were equally spaced there would be one for each 4.5 

 dm. square of surface; but since the temperature of the chamber would 

 tend to vary more at the top than at the bottom, more elements were 

 installed in the upper than in the lower parts of the chamber to increase 

 the sensitivity and integrate a larger number of sections of the walls. 

 There are accordingly 16 elements in the ceiling and 10 in the floor. In 

 the sides are five rows, with 14 elements in each row except the first one 

 from the top, from which one is missing because the space in which it 

 would be located is occupied by the window. The five rows are not quite 

 equally separated, the two upper rows being slightly nearer together 

 than the three lower ones, in accordance with the idea that the tempera- 

 ture of the upper section would tend to vary more than that of the lower 

 one. These thermoelements are joined in groups in such manner that a 

 difference between the temperature of the copper wall and that of the 

 zinc wall may be detected in certain portions of the walls without regard 

 to conditions in other parts. One group includes the 16 elements in the 

 top; another the 28 elements in the two upper rows of the sides, called 

 the upper zone; a third, the 42 elements in the three lower rows of the 

 sides, called the lower zone; and a fourth group, the 10 elements in the 

 bottom. The thermoelements in each group are connected in series 

 by heavily insulated No. 18 copper wire, and the same sort of wire leads 

 from the terminals of each group to a multiple point switch on the 

 observer's table by which the groups may be connected successively 

 with the galvanometer. It is also possible to connect all 95 thermo- 

 elements in series as a whole with the galvanometer and thus observ^e 

 the average difference between the temperature of the copper wall as a 

 whole and that of the zinc wall as a whole. 



