( 44 1 ) 
? 
any confiderable Artery, muft neceifarily be moved by e- 
very Pulfation of fuch Artery, fo this Pulfat. ion (unlefs 
underftood in fucli Manner as I {hall hereafter explain) 
can no ways be admitted as the true Diagnoflick, 
whereby to fpecify the Difference between this Kind 
of Tumor and any other. 
An Aneuryfm is found moft commonly to fucceed 
Falls, .Vomitings, Labour-drains, and fuch other Mo- 
tions or Indifpohtions of the Body as, by cotnprefling 
the great Branches of an Artery, any ways flop the pro* 
greflive Motion of the Blood, 
It is obvious that, as theSe&ion of the Artery above 
the Comprelfure muff in its natural State be fotnetimes 
very incapable of containing at once the whole Qu enti- 
ty of Blood, which ought only to have pafs’d thro’ it 
fuccefively ; and as the Force of the Heart may fre- 
quently exceed the Refiftance it may meet with from 
the Coats of the Artery j fo the Confequence of fuch 
a Stop to the progreflive Motion of the Blood, ( may oc- 
casion either a Rupture of the Artery, or a 'Diftenfion 
of the Artery without a Rupture, or a Rupture of the 
internal Coats of the Artery, and a *Diftenjion of its 
external Coat* 
A Rupture of the large Branches of the Aorta ne* 
ceffarily allow fo plentiful Effufions of the Blood, as 
to occafion immediate Death ^ while the Capillaries may 
be burft without any other Injury, but a flight E- 
ehymofis , and the Tumor form’d by the Effufion from 
them will be diffufed and fuperficial. 
A Rupture of the mean Branches (fuch I intend, as 
defcend between the Tibia and Fibula , the Radius 
and Vina, &c.) will be attended with a confiderable 
Effulion of Blood ; but as the Blood will find a Palfage 
N n n 2 be* 
