of Man, or Economic Coefficient of the Human Machine. 363 



Therefore the power necessary to overcome the friction is exactly 

 balanced by the weight at the end of the lever, and the work done will 

 be a function of the weight multiplied by the length of the lever, or 

 may be expressed as the work done in raising the weight by means of 

 a cord wound round a drum, having for its radius the distance between 

 the suspension of the lever and the end of the beam where the weight 

 is hung. It should be understood that the beam is balanced by a 

 counterpoise before the weight is suspended to its extremity. 



The only objection that could be made to the use of this instrument 

 might be the friction to overcome on turning the wheel ; but there is no 

 appreciable friction, the wheel revolving on ball-bearings like those of i 

 a bicycle. The weight can be altered, and it will be readily found that 

 if a person works the wheel as hard as he can for a given time, by: 

 doubling the weight at the end of the lever the number of revolutions 

 he can make in that same time will be half that registered with the 

 lighter weight. 



The experiment in the calorimeter is made as follows : 



The subject is shut up in the chamber as usual, and there he remains 

 for thirty minutes quite quiet ; during that time the temperatures are 

 recorded, and the water from the melted ice is collected, thus the heat 

 given out in the state of repose is determined. Then the person is let 

 out of the calorimeter, and the chamber left full open for its ventila- 

 tion, and about twenty minutes later he returns into the chamber. At 

 once the work of turning the handle begins, to be continued for about 

 half an hour. Then a rest is taken for another half hour inside the 

 calorimeter, and the experiment is over. 



By so doing the heat emitted in the state of rest is first determined ; 

 this is followed by the determination of the heat given out when at work 

 and while the body is returning to its normal state of rest. It might 

 be thought that the amount of work done had better be determined by 

 first working the wheel perfectly free and therefore effecting no work, 

 and then putting on the brake while the lever is weighted and doing a 

 certain amount of work ; the heat emitted in the first case would be 

 subtracted from that given out in the second. This plan, however, is 

 not admissible, because, at any rate, no work can be done without 

 moving the arm, so that the arm is a necessary factor of the work. 



The first question was to ascertain whether the mean relation of the 

 oxygen absorbed under work to the calories emitted was the same as 

 the corresponding mean relation in the state of rest. In order to settle 

 this point, the CO 2 emitted and absorbed were determined while in 

 the calorimeter, together with the calories, both when sitting quiet and 

 during exercise, the relation at rest having been fully investigated in 

 our last paper and found to be 1 : 4'000.* 



* It was stated in the previous paper that Him had found that while sitting 

 quiet, 1 gram of oxygen gave rise to a mean of 5'22 calories. 



