Heat-production Associated with Muscular Work. 101 



production. Measurements of the resistance of a sample of the iron wire 

 used in the construction of the calorimeter " thermometer " were carefully 

 undertaken by Dr. Chapman, to whom, in the earlier stages of the con- 

 struction and calibration of the calorimeter, I am indebted for a considerable 

 amount of help. It was then found that a change of 1° C. in the 

 temperature of this wire was accompanied by a change in the resistance 

 such as, applied to the amount of wire in the calorimeter, would corre- 

 spond with a change of 2*54 ohms in resistance ; and this, seeing that 

 0"01 ohm involves a change of 1/6 kalorie, would involve a change of 

 42*3 kalories. Thus the thermal "water equivalent" of the calorimeter 

 would seem to have the high value of 42 - 3 litres. 



As to the storage space within the calorimeter, that is a figure which, for 

 the present, is of much less importance, since the data given are taken from a 

 time of work-performance when such storage is practically at an end. The 

 storage space is, as we have found, less than the total internal air space. This 

 fact has been ascertained by my assistant, Dr. Duffield, in calibration 

 experiments, in which carbonic acid was delivered into the calorimeter at 

 a definite rate, and comparison was made between this rate of entrance 

 and its observed rate of departure in the air current. These experiments 

 are in progress and will be described later by Dr. Duffield. In the mean- 

 time, for the purposes of this communication, I have taken the storage 

 space as less than the total space by a quantity equivalent to that of the 

 air entering over a single five-minute period. It is probable that later I 

 may have to increase this subtraction, but the relative unimportance of the 

 point may be judged from the values given below. These are the average 

 figures provided by the set of experiments described as " Group D " in the 

 next section, and from them it is possible to see how small the figures for 

 the storage of aqueous vapour are, and how little their modification will 



mean when the " storage space " is better known. 



Data from Group D (see p. 109). Kals. 



(I) Heat carried away by the water-stream 303 



(II) Heat carried away with the aqueous vapour of the air-stream... 28 



(III) Heat stored in the water-vapour of the calorimeter 2 



(IV) Heat stored in the walls of the calorimeter (calorimeter tem- 



perature) 10 



(V) Allowed for difference between the temperatures of the entering 



and leaving air 1 



(VI) Allowed for change in the rectal temperature of the subject ... 2 



Heat production 346 



