( 443 ) 
confider’d abftra&edly from its Preffures) be worfe (if 
fo bad) than from a varicous Vein. 
Again, they who conceive an Aneuryfm to be a Rup- 
ture of both Coats of the Artery, oppofe their Opini- 
on, who imagine the internal Coax, to be ruptured, and 
the external to be diftended , by comparing the two 
Coats in Queftion, and urging, that, as the internal 
Coat is fo much thicker than the external, it feems im- 
poflible thelaft fhou’d be fufficient to refill a Force ca- 
pable of deltroying the firft. Were thefe two Coats fi- 
milar as to their Stru&ure, we might then compute their 
Strength by their Thicknefs, and this Argument wou’d 
be of much greater Force than at prefent it can be } be- 
caufe the internal Coat bei ng.com pofed of annular Faf- 
ciculi , whofe Sides have but a very weak Cohelion, 
their Power of refilling will not be meafurable by the 
Strength of thofe Annuli ; but by the Force with 
which they adhere laterally . And on the other Hand, 
the external Coat being com pofed of Fibres equally in- 
terwoven, , and of a quite different Compofition, it may 
either exert a greater Refiftance, or be capable of much 
greater Dilatations than the internal. 
But that Autopfy may evince the Truth of this Dif- 
ference in the Strength of thefe Coats, it will be found 
by any one who pleafes to try the Experiment, that 
by blowing into the Pulmonary Artery, the internal 
Coat will foon burft, and the external form it felf into 
aneurifmous Tumors, ( which Experiment was accord- 
ingly try'd before the Society , to their Satisfaction.) 
Upon confidering all which, and having, by Order 
of the Society , both privately and publicity examin’d 
the Aneuryfm before us, which I find to be round like 
other extravafate Tumors, unlefs when controuled by 
any 
