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XXXVI. A Dtfquljitmi cojtcerning certain 
Flue?2ts^ which are ajjignable by the Arcs 
of the Conic ScSiions ; wherein are invejii- 
gatea fome new and ufeful theorems for 
cotnputing fuch Fluents : By John Lan- 
den, F. R. S. 
Read June 6 , A /TR. Mac Laurln, In his Treatlfe of 
1771- JVJ. Fluxions, has given fundry very 
elegant Theorems for computing the Fluents of cer- 
tain Fluxions by means of Flliptic and Flyperbolic 
Arcs ; and Mr. D’Alembert, in the Memoirs of the 
Berlin Academy, has made fome improvement upon 
what had been before Written on that fubjed:. But 
fome of the Theorems given* by thofe Gentlemen 
being in part expreffed by the difference between 
an, Arc of an Hyperbola and its Tangent, and fuch 
difference being not diredly attainable, when fuch 
Arc and its Tangent both become infinite, as they 
will do when the whle Fluent is wanted, although 
fuch Fluent be at the fame time finite ; thofe The- 
orems therefore in that cafe fail, a computation 
thereby being then impradicable, without fome far- 
ther help. 
The fiipplying that defed T confidered as a point 
of fome importance in Geometry, and therefore I 
3 ' carneftly 
