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petim dato per prscedentes [tres] Regulas elicitur , eadem queth* 
bet alia quant it as ex moment o fuo Jic dato elicietur. Exemplo res 
fist clarior. And after Tome Examples he adds his Method 
of Regreffion from the Area, Arc, or folid Content, to the 
Abfcifia ; and fhews how the fame Method extends to Me- 
chanical Curve-, for determining their Ordinates, Tangents, 
Areas, Lengths, (jrc- And that by afluming any Equation 
expreffing the Relation between the Area and Ablcifla of a 
Curve, you may find the Ordinate by this Method. And 
this is the Foundation of the Method of Fluxions and Mo- 
ments, which Mr. Newton in his Letter dated Oclob. 24, i 676 
comprehended in this Sentence. Data <equatione quotcunque 
fluent es quantitates involventc , invenire Fluxiones ; & vice vet fa. 
fn this Compendium Mr. Hevrton reprefents the uniform 
Fluxion of Time, or of any Exponent of Time by an Unit ; 
the Moment of Time or of its Exponent by the Letter 0 ; the 
Fluxions of other Quantities by any other Symbols; the Mo* 
ments of thofe Quantities by the Redtangles under thofe 
Symbols and the Letter 0 ; and the Area of a Curve by the 
Ordinate inc’ofed in a Square, the Area being pat for a Flu- 
ent and the Ordinate for its Fluxion. When he is demon- 
ftrating anyPropofition he ufesthe Letter 0 for a finite Moment 
of Time, or of its Exponent, or of any Quantity flowing 
uniformly, and performs the whole Calculation by the Geo- 
metry of the Ancients in finite Figures or Schemes without 
any Approximation : and fo foon as the Calculation is at an 
End, and the Equation is reduced, he fuppofes that the 
Moment 0 decreafes in infinitum and vanifhes. But when he 
is not demonftrating but only inveftigating a Propofition, for 
making Difpatch he fuppofes the Moment 0 to be infinitely 
little, and forbears to write it down, and ufes all manner of 
Approximations which he conceives will produce no Error in 
theConclufion. An Example of the firft kind you have in 
the End of this Compendium, in demonflrating the firft of 
the three Rules laid down in the Beginning of the Book. 
F f 4 Exam- 
