( 161 ) 
I have alfo applied this Doctrine to the Defcrip- 
tion of Lines through given Points. But I fuppofe 
I have faid enough at prefent on this Subjedt; and 
fhall conclude, after obfervingthat in the abovemen- 
tioned Treatife, I have given an eafy Theorem for 
calculating theEefiftance of the Medium when a 
given Curve is defcribed with a given centripetal 
Force in a refilling Medium, which I ihall here re- 
peat, becaufe it has been mifreprefented in a foreign 
Journal. 
Let V exprefs the centripetal Force with which 
the Body that is fuppofed to defcribe the Curve, is' 
adted on in the Medium ; let v exprefs the centri- 
petal Force with which the fame Curve could be de- 
V 
fcribed in a Void j fuppofe .3= — , and the Refi- 
nance Ihall be proportional to the Fluxion of z> mul- 
tiplied by the Fluxion of the Curve, fuppofing the 
Area defcribed by a Ray, drawn from the Body to 
the Center of the Forces, to flow uniformly. Let 
this Theorem be compared with what the celebrated 
Mathematician mentioned by that Journalill has 
given on the fameSubjedt, and it will eafily appear 
what judgment is to be made of his Aflertion ; and 
fince leveral Perfons, and particularly the Gentleman 
mentioned above in this Paper, tellify that I com- 
municated to them rhis Theorem before any Thing 
was publiihed on this Subjedt by the learned Ma- 
thematician he names, his Obfervation on this Oc- 
cafion mull appear the more groundlefs. 
From this Theorem, I draw this very general 
Corollary, that if the Curve is fuch as could be de- 
fcribed in aVoid by a centripetal Force, varying ac- 
X z cording 
