56 



ON THE FUNCTIONS OF THE HEART AND AftTERlES. 



Time of cer 

 tain birds ap- 

 pearing and 

 dijappearing . 





EARLIEST APPEARANeB. 



LATEST. 





1806 



1807 



1808 



1809 



1810 



1808 



1809 



Hirundo rustica, 

 Comraoa swallow. 



Apr. 



2 



May 

 1 



Apr. 



18 



Apr. 



28 



Apr. 

 21 



Oct. 

 17 



Oct. 

 18 



Aug. 

 14 



Oct. 

 3 



Oct. 

 16 



Aug. 

 13 



Hirundo urbica, 

 Martin. 



Apr. 



26 



May 



1 



May 



1 



May 

 5 



Apr. 

 21 



Hirundo apus. 

 Swift. 





May 

 l6 



May 

 14 





May 

 19 



Jynx, or yunx tor- 

 quilla, Wrynec}c. 



May 

 1 



Apr. 

 30 



May 

 1 





Apr. 

 21 



VII. 



Mechanical 

 motion in a 

 living body- 

 subject lo the 

 Jaws of dead 

 matter; 



but the vital 

 powe:scan in 

 St 1 lite pro 

 cesses to coun- 

 if ract different 



The Croonian Lecture. On the Functions of the Heart and 

 Arteries. Bij Thomas Young, M. D. For, Sec. R. S*. 



JL HE mechanical motions, which take place in an animal 

 body, are regulated by the same general laws as the motions 

 of inanimate bodies. Thus the force of gravitation acts 

 precisely in the same manner, and in the same degree, on 

 living as on dead matter; the laws of optics are most accu- 

 rately observed by all the refractive substances belonging to 

 the eye ; and there is no case in which it can be proved, that 

 animated bodies are exempted from any of the affections to 

 which inanimate bodies are liable, except when the powers 

 oi' life are capable of instituting a process, calculated to 

 overcome those affections by others, which are commensu- 

 rate to them, and which are of a contrary tendency. Fojr 



f Philos, Trans, for 1809, p. 1. 



exaraplcj 



