1 6 6 Hcemajiatks. 
Judgment of the skilful Phyfician to know 
when and in what Proportion to abate by this 
Evacuation the Force of the Blood. And in 
general fince a human Body is fo curioufly 
complicated an Engine, that the mutual Har- 
mony of fuch innumerable Circumftances muft 
concur to its Welfare, no wonder that it re- 
quires the mafterly Hand of the skilful Phyfi- 
cian to reftify it when out of order. Were the 
bold Empiric but duly fenfible of this, he 
would not furely dare to intermeddle, but 
Ignorance is his beft Plea. 
25. Tho* the Strength of the Coats of the 
finer Arteries and Vcinsare proportionably thin- 
ner and weaker as they grow lefs and Icfs ; yet 
fince the ,Sum of the Preflure of equally high 
Columns of Water againfl: the Sides of con- 
taining cylindrical Tubes of different Diame- 
ters is proportionable to the Surfaces of thofe 
Tubes ; the Strength therefore of their Coats 
may be equally as much fuperior to the uc- 
moll: Etforts of the Blood in them, as thofe 
of the larger ones are to the Force of their 
contained Blood ; they arc therefore propor- 
tional to their Circumferences. 
24. But as to the finer fecretory VefTels and 
Lymphatics which arife from the capillary 
Arteries> 
