SOURCES OF MUSCULAR FORCE. 



The mean of these estimates is 340.2 ft. tons, or 762,048 ft. pounds = 

 105,605 kilogrammetres, which closely accords with the estimate of Professor 

 Bonders. 1 In his address at the meeting of the British Association, at Ox- 

 ford, Professor Haughton estimated the daily external work of a working 

 man at 353.75 foot tons, and adds 133 foot tons for the work requisite to 

 maintain the circulation and respiration. Ranke 2 gives the following table 

 from Redteubacher : 



The amount of work accomplished in eight hours in Kilogr. in eight hours. 



1. Man, weighing on the average 70 Uilog., working without 



machine, . 316,800 



" with a lever (Hebel), 158,400 



" with a windlass (Kurbel), 184,320 



" with a whinsey or gin, ...... 207, 360 



" with a treadwheel, 241,020 



" with sin inclined plane, 24, 345,000 



2 Horse, weighing on the average 280 kilog., working with- 

 out a machine, ....... 2,102,400 



" with a gin, 1,152,000 



3. Ox, weighing on the average 280 kilog., without ma- 



chine, 1,382,400 



" with a gin, . 1,123,200 



4. Mule, weighing on the average 230 kilog., without ma- 



chine, 1,497,600 



" with gin, 777,600 



6 Ass, weighing on the average 168 kilog., without ma- 

 chine, 8<>4,000 



" with gin, . 316,800 



Reducing these results to a general measure for a given weight, Ranke 

 estimates that 



1 kilog. of human muscle works in 1 sec., without machine, 0.157 kilog. 



" " ox " " " 0.172 " 



" ass " " " 0.178 " 



" mule " " " 0.222 " 



" horse " " " 0261 " 



He calculates eight hours' walking to be equivalent to 200,000 kilogr. 



689. Sources of Muscular Force. Muscle has been defined by an able 

 chemist to be a machine by which heat is converted into mechanical force; 

 and the results of numerous recent researches tend to show that the source 

 of the primary heat is to be looked for in the oxidation of both the nitro- 

 genous and of the non-nitrogenous constituents of the blood ; the combina- 

 tion taking place partly and principally within the bloodvessels (Heaton), 

 but partly also in those portions of the blood which, escaping from the ves- 

 sels, supply the tissue with the materials requisite for its nutrition. That 

 nitrogenous substances are oxidized during muscular exertion is sufficiently 

 proved by the necessity that exists for their free supply in groups of men, 

 as navvies, prizefighters, etc., who have to maintain severe and protracted 

 exertion, as well as by the fact ascertained by Parkes (411) and Flint 

 ( 411), that a slight increase in the amount of the products of the disinte- 

 gration of the nitrogenous constituents of the body does take place during 

 exercise, whether the diet have contained a regulated amount of nitrogen, 

 or has been wholly restricted to non-nitrogenous substances. That the force 

 daily exerted by the muscles of a laboring man is, however, not exclusively 



1 See Dr. Moor's translation of his paper in Humphry and Turner's Journal of 

 Anatomy, vol. i, 1867, p. 168. 



2 Grundziige der Physiologie, 1868. 



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