150 APPENDIX II. 



the lake of Brienz. This mountain can be ascended 

 by a very steep path from Iseltwald, which was of 

 course favourable for the experiment, and there is 

 an hotel on the summit which allowed the experi- 

 menters to pass the following night under tolerably 

 normal circumstances. The following is their own 

 description and estimate of the amount of work per- 

 formed in the ascent.* 



" Let us now inquire how much work was really 

 really done by our muscles. One item necessary 

 for the reply is already at hand, viz., the height of 

 the summit of the Faulhorn above the level of the 

 lake of Brienz multiplied by the weight of the 

 body ; the former reckoned in metres, the latter in 

 kilograms. The weight of the body with the equip- 

 ments (hat, clothes, stick) amounted to 66 kilo- 

 grams in Fick's case, and 76 in Wislicenus's. The 

 height of the Faulhorn above the level of the lake 

 of Brienz is, according to trigonometric measure- 

 ments, exactly 1956 metres. Therefore Fick per- 

 formed 129,096 (1956 x 66) and Wislicenus 

 148,656 (1956x76) metrekilograms of muscular 

 work." 



But in addition to this measurable external work 

 there is another item of force " which can be ex- 

 pressed in units of work; and though its value 

 cannot be quite accurately calculated, yet a tolerable 

 approximation can be made. It consists of the force 

 consumed in respiration and the heart's action. 

 The work performed by the heart has been esti- 

 mated, in a healthy full-grown man, at about 0'64 

 * Phil. Mag., vol. xxxi., p. 496, 1866. 



