40 Prof. TyndalPs Notes on Scientific History, 



38. In the same way Mayer, taking the data furnished by 

 Liebig regarding the prisoners and soldiers at Giessen, deter- 

 mines the following relations for a man. 1. The mechanical 

 effect is to the total consumption as 95*7 : 540 = 0*177. 2. The 

 mechanical effect is to the surplus consumption of the man at work 

 as 957 : 285 = 0-336. 3. The generation of heat in the resting 

 man to that in the working man as 255 : 540—95*7 = 0-57. 



39. In these calculations, he continues, I have confined my- 

 self to the consumed carbon. If the heat of combustion be set 

 equal to the carbon + the hydrogen, the additional heat of the 

 hydrogen may be regarded as nearly = ^th of that of the carbon. 

 According to the individual constitution and habits of life, the 

 labour and the consumption must be liable to considerable va- 

 riations. The above results, however, serve to demonstrate the 

 following propositions : — 



(1.) The surplus nutriment consumed in the working or- 

 ganism completely suffices to account for the work done. 



(2.) The maximum mechanical effect produced by a working 

 mammal hardly amounts to £th of the force derivable from the 

 total quantity of carbon consumed. The remaining Jths are 

 devoted to the generation of heat. 



VI. 



40. In order to enable them to convert chemical force into 

 mechanical work, animals are provided with specific organs, 

 which are altogether wanting in plants. These are the muscles. 



41. To the activity of a muscle two things are necessary: — 

 1. The influence of the motor nerves as the determining condi- 

 tion ; and 2. the material changes as the cause of the mecha- 

 nical effect. 



42. Like the whole organism, the organ itself, the muscle, has 

 its psychical and its physical side. Under the former we include 

 the nervous influence, under the latter the chemical processes. 



43. The motions of the steamship are performed in obedience 

 to the will of the steersman and engineer. The spiritual influence, 

 however, without which the ship could not be set in motion, or, 

 wanting which, would go to pieces on the nearest reef, guides, 

 but moves not. For the progress of the vessel we need physical 

 force — the force of coal ; in its absence the ship, however strong 

 the volition of its navigator, remains dead. 



VII. 



Thus does this remarkable man, at a time when the writings 

 of the most celebrated scientific professors were beset with 

 mysticism as regards the operations of the vital force, pour light 

 upon the darkness, and bring the processes of the animal body 



