1 76 Dr. Winn on a remarkable Property of Arteries. 



action of the arteries. The precise quantity of heat given 

 off during each beat of an artery, it would be exceedingly 

 difficult, perhaps impossible, to discover ; but if we admit the 

 development of only a very small quantity, it necessarily fol- 

 lows, from the circumstance of the action of the arteries being 

 in incessant operation during life, that the heat must quickly 

 accumulate to a great extent, and that the body unless cooled 

 by the functions of the skin and lungs, would in a short space 

 of time become preternaturally hot. 



The following |physiological and pathological facts appear 

 to corroborate the view I have taken of the mechanical source 

 of heat. 1 st, The minute distribution of the arteries to every 

 part of the system ensures a general and equal distribution 

 of heat. 2ndly, The ossification of the arteries in old age, by 

 diminishing their elasticity, is a probable cause of the dimi- 

 nution of animal heat at the close of life. 3rdly, The in- 

 creased warmth of the body from exercise appears to be more 

 readily explicable upon the principle of increased force in the 

 arteries rather than that of increased vigour in the functions 

 of the lungs, in as much as the immediate effect of exercise is 

 evidently to embari'ass the breathing, as shown by the hur- 

 ried respiration. 4thly. In many diseases of the lungs where 

 its functions are all at fault at a time when the arteries are 

 beating with increased violence, the heat of the body is found 

 to be above the usual standard. 5thly, Medicines which di- 

 minish the contractility and elasticity of the arteries almost 

 invariably reduce the heat of the body. 6thly, The heat of 

 local inflammations, in cases where the constitution does 

 not sympathize to any extent, cannot be easily referred to 

 any other source, as the arteries immediately in the neigh- 

 bourhood of the affected part are throbbing with violence at 

 a time when its capillaries (which are supposed to play so 

 large a share in the chemical theory of heat) are generally 

 considered to be entii'ely arrested. Many facts of a similar 

 nature could be enumerated, but enough I think have been 

 stated to establish the truth of the theory in question. 



Of the nature of the mechanical force I have been investi- 

 gating little can be said ; it may possibly be a kind of inter- 

 molecular friction. It is clearly, however, of a different na- 

 ture from ordinary friction, and which has also been consi- 

 dered a cause of animal heat; but I think erroneously so, for 

 on examining the mechanism of the human body we find that 

 everywhere the most efficient means of defence have been pro- 

 vided against its effects, as seen in the various synovial, mucous, 

 and serous membranes, &c. It is not the province, however, 

 of the physiologist to speculate on the essential nature of me- 



