[ J)< ] 
how great focvcr. The Points of the Conchoid are 
determined by drawing; right Lines from a civen 
Centre, and upon thclc produced from the Afym- 
ptote, taking always a given right Line ; fo that the 
Curve never meets the Afymptote, but continually 
approaches to it, becaufe of the greater and greater 
Obliquity of this right Line. The Third is the Lo- 
garithmic Curve, wherein the Ordinates, at equal 
Diftances, dccreafe in Geometrical Proportion, but 
never vanifh, becaufe each Ordinate is in a given 
Ratio to the preceding Ordinate. Geometrical 
Magnitude is always underftood to confift of Parts; 
and to have no Parts, or to have no Magnitude, are 
confidercd as equivalent in this Science *. There is, 
however, no Neceftlty for confidering Magnitude as 
made up of an infinite Number of fmall Parts ; it is 
fufficient, that no Quantity can be fuppofed to be fo 
fmall, but it may be conceived to be diminifhed fur- 
ther ; and it is obvious, that we are not to eftimate 
the Number of Parts that may be conceived in a 
given Magnitude, by thofe which in particular deter- 
minate Circumftances may be actually perceived in it 
hy Senfe; fmee a greater Number of Parts become 
vifible in it by varying the Circumftances in which 
it is perceived. 
It is hardly poftible to give a tolerable Extraft of 
this or the following Chapters, without Diagrams 
and Computations : Wefhall therefore obferve only, 
that after giving fome plain and obvious Inftanccs, 
wherein a Quantity is always increafing, and yet never 
* See Euclid's Elements, Def. I. Lib. I-» 
amounts 
