100 



they call globules of the second order. But we are 

 not to stop here. There are in the blood a great many 

 particles six times less than these. Globules of the se- 

 corrd order are compounded of these smaller ones, 

 which therefore are globules of the third order. 



Farther. There are innumerable blood vessels of 

 such smalluess, that none of the abovemeutioned 

 globules can pass them ; so that we cannot but suppose 

 still smaller globules. The diameter of some vessels is 

 less than the eighth part of the diameter of a red glo- 

 bule, so that the particles passing through them must 

 be above five hundred times less than those globules. 

 Nay, on a careful examination, we perceive vessels 

 narrower than the tenth part of the diameter of a red 

 globule, which consequently can transmit spherules no 

 greater than the thousandth part of a red globule. 



On the whole then, each globule of the first order 

 is made up of six of the second; these of six of the 

 third, those of six of the fourth, these of six of the 

 fifth, and so on, And accordingly we find the globules 

 of the highest orders may be broken down into their 

 compounding particles. 



The diameter ot a common red globule is about the 

 1938th part of an inch. The diameter of a globule of 

 the tenth order is less than the 400 3 000th part of an 

 inch. 



Anatomists and physicians have generally determined 

 the quantity of blood in the human body to be between 

 fifteen and twenty-five pounds ; but Dr. Keil shews 

 from many instances of profuse haemorrhages, that a 

 far greater quantity must be allowed, otherwise the 

 patient could never have furnished, or at least survived 

 such evacuations, the least of which exceeded the 

 whole quantity of blood supposed to be in the body. 



In reality the quantity oi blocd in a human body is 

 difficult to be determined. Bleeding to death,, the 

 usual method, can never shew what is its true quatiti. 

 ty ; because no animal can bleed longer than while 

 the great artery is full, which will require a longer or 

 a shorter time as the wouiided artery is smaller or 



