C 4 ° 5 ] 
that an Operation is fuppofed to be performed on the 
Quantity that is under the radical Sign. The Ope- 
ration is indeed in this Cafe imaginary, or cannot 
fucceed 5 but the Quantity that is under the radical 
Sign, is not lefs real on that Account. The Author 
mentions thofe things briefly, becaufe they belong 
rather to a Treatife of Algebra than of fluxions, 
wherein the common Algebra is admitted. 
In order to avoid the frequent Repetition of figu- 
rative Expreflions in the Algebraic Part, the Fluxions 
of Quantities are here defined to be any Meafures of 
their refpettive Rates of Increafe or Decreafe, while 
they are fuppofed to vary (or flow) together. Thefe 
may be determined by comparing the Velocities of 
Points that always deferibe Lines proportional to the 
Quantities, as in the Firft Book; but they may be 
likewife determined, without having recourfe to 
iuch Suppofitions, by a juft Reafoning from the 
fimultaneous Increments or Decrements themfelves. 
While the Quantity A increafes by Differences equal 
to a , 2 A increafes by Differences equal to 24, and 
(fuppofing m and n to be invariable) ~ increafes by 
Differences equal to — , and therefore at a greater or 
lefs Rate than a, in proportion as m is greater or lefs 
than n. Thus a Quantity may be always affigned 
that fhall increafe at a greater or lefs Rate than A , 
(/. e. fhall have its Fluxion greater or lefs than the 
Fluxion of A ) in any Proportion } and a Scale of 
Fluxions may be eafily conceived, by which the Flu- 
xions of any other Quantities of the fame kind may 
be meafured. 
Let 
