146 



ANIMAL MECHANICS. 



From the weight of the heart and the work done by it in one 

 day, we can calculate the work done by the heart per ounce, 

 as follows : — 



Work done by the human heart in foot lbs. per oz. per minute, 



124.208 x 2240 



= — i—= 20.576. 



9.39 x 24 x 60 



On comparing this result with the work done by other 

 muscles, given in Tables VII. and VIII. (p. 62), we observe 

 that the work done by the heart in a given time (20.576) ex- 

 ceeds considerably the work done by the muscles in a boat 

 race (15.17). In a boat race, the labour can be maintained 

 for a few minutes only ; while the heart labours at a greater 

 rate throughout the whole of life. 



There is another mode of exhibiting the wonderful energy 

 of the heart which is worth stating, more especially as it 

 affords a means of comparing my own result with that of Pro- 

 fessor Helmholtz, the data of whose calculation I am not ac- 

 quainted with. Let us suppose that the heart expends its 

 entire force in lifting its own weight vertically, then the 

 height through which it could lift itself in one hour is thus 

 found, by reducing the daily work done in ft. tons to the 

 hourly work in foot ounces, and dividing by the weight of 

 the heart in ounces. 



Height through which the human heart could raise its own weight in one 

 hour, 



124.208 x 2240 x 16 



= — = 19754 ft. 



24x9.39 



Professor Helmholtz* states as the result of his own calcu- 

 lations, that the heart could raise its own weight through 

 20250 ft. in one hour. It has been already stated (p. 52), 

 that an active climber can ascend 9000 ft. in nine hours, 



* "Medical Times and Gazette," May 14, 1864, p. 529. 



