36 



CALORIMETERS FOR STUDYING RESPIRATORY EXCHANGE, ETC. 



sponds to the rear section of the chair calorimeter and to the sides of the 

 bed calorimeter. No. 3 corresponds to the front of the chair calorimeter 

 and is without communication with the bed calorimeter. No. 2 connects 

 with the bottom of both calorimeters. 



It will be seen from the diagrams that each of these resistances can be 

 connected at will with either the bed or the chair calorimeter and at such 

 points as are indicated by the lettering below the numbers. Thus, section 

 1 can be connected with either the point A or point a on fig. 17 and thus 

 directly control the amount of current passing through the corresponding 

 resistance in series with the lamp in the air-current. The sliding contacts 



I5~ PER SECTION 



S LID INC CONTACT 



Fig. 18. — Diagram of rheostat and resistances in series with it. At the right are 

 shown the sliding contacts, and in the center places for lamps used as resist- 

 ances, and to left the sections of wire resistances. 



at present in use are ill adapted to long-continued usage and will therefore 

 shortly be substituted by a more substantial instrument. The form of re- 

 sistance using small lamps and the resistance wires wound on asbestos lumber 

 has proven very satisfactory and very compact in form. 



TEMPERATURE RECORDER. 



The numerous electrical, thermometric, and chemical measurements neces- 

 sary in the full conduct of an experiment with the respiration calorimeter 

 has often raised the question of the desirability of making at least a por- 

 tion of these observations more or less automatic. This seems particularly 

 feasible with the observations ordinarily recorded by the physical observer. 

 These observations consist of the reading of the mercurial thermometers 

 indicating the temperatures of the ingoing and outcoming water, records 



