,40 



and of the head [vide c, frontlfpiece]. It is from 

 this fource that the blood is formed ; and it is thus 

 that food goes to the fupport of the conftitution by 

 forming of blood. 



^ The bbod, which is univerfally and continually 

 circulating through the machine, confifts of a folid 

 part fufpended in a fluid, which, en being cold, fe- 

 parate from each other. To circulate this fluid, 

 refervoirs and canals arc neceflary : the refervoirs 

 are the cavities of the heart, and the canals are call- 

 ed arteries and veins. The arteries carry it from the 

 heart [fee the plate^ where o reprefents the vein, 

 and that without a letter, next to it, the artery]. 

 Thofe carrying the blood to the heart are the veins. 

 There is what is called a double circulation ; that 

 is, while part of the blood is pafling over the refl of 

 the body, part is paflJing through the lungs, but fo 

 that, alternately, all pafles through the lungs, and 

 all through the other parts of the body. As the 

 blood paflcs through the lungs, it is aded on by the 

 air, becomes pure, and receives heat; and, as it 

 paffes over the refl; of the bod}^, it gives out the 

 purity and heat which it received from the air, 

 and the nourifliment which it received from the 

 chyle, thus to form, increafe, and nourifli the va- 

 rious parts of the body, and to fupport the fecretions 

 of the different fluids. The force with which the 

 heart acts is fo contrived, that at one moment it re- 



