o 
( 3*9 ) 
theVefTel;and in a natural State they (hut that Railage, and 
fo prevent the Blood from recoiling into the fame, if it 
fhould endeavour to return. But in this cafe, by realon 
of its contra&ed Narrownefs and Thicknefs, not being 
able to clofe or (hut the PaiTage, the Blood flowd back 
again into the Cavity, which it had gradually enlarged, 
and dilated to the Bignefs we fee. Befides the Mufcttlar 
Valves not being duly qualified for the Performance of 
their Office, the Blood recoiled into the Auricle , which it 
had diftended in the like manner This conftant Re» 
gurgitation or Reflux of the Blood is befides fufficient of 
itsfelf, to produce this extraordinary trembling or -era A? 
f/, 6 s xapS'lctL, as the Greeks call ir. 
I V. A ready Defotiption and Quadrature of a Curve 
of the Third Order, refembling that commonly 
call'd the Foliate. Communicated hy Mr. Abv. de 
Moivre, F. % S,„ 
I Have look’d a little farther into that Curve which fell 
lately under my confideration. It is not the Foliate 
as l did at firft: imagine, but I believe it ought not to 
make a Species diftindlfrom it. A E B( Fig. i.) is the Curve 
I thus describe. Let A B and B K be perpendicular to 
each other. From the point A draw A R cutting B K in 
/?, and make R E — B R, the point E belongs to the 
Curve Draw B C making an Angle of 45 grad, with A B, 
this Line B C touches the Curve in B ; from the point E 
draw ED perpendicular to BC , and calling B D, x\ 
D B, y ; A B, a ; and making = 0, the Equation 
belonging to that Curve is -f- x X J J r x yy — nxy 
jA — v 
or — „ X y. Taking BG — A B, and drawing G P 
x ~y ■. 
perpendicular to BG, P G is an Afymptete. In the Foliate 
F. f f 3 &h <u.- 
4 
