•[ 51 ° ] 
that there is no Foundation in Nature for, nor can 
any valuable End be fervcd by applying Meafure to 
any, thing but what has thefe two Properties. Firft 
it mud admit of Degrees of greater and lcfs. Se- 
condly, it muft be affociated with, or related to 
fomething that has proper Quantity, fo as that when 
one is inereafed the other is increafed, when one is 
diminifhed, the other is diminiflied alfo ; and every 
Degree of the one muft have a determinate Magni- 
tude or Quantity of the other correfponding to it. 
It fometimes happens, that we have Occafion to 
apply different Meafures to the fame thing. Centri- 
petal Force, as defined by Newton , may be mea- 
fured various Ways, he himfelf gives different Mea- 
fures of it, and diftinguifhes them by different 
Names, as may be feen in the above-mentioned 
Definitions. 
In reality, I conceive that the applying of Meafures to 
things that properly have not Quantity, is only a Fi&ion 
or Artifice of the Mind, for enabling us to conceive 
more eafily, and more diftinttly to exprefs and demon- 
ftrate, the Properties and Relations of thole things that 
have real Quantity. The Propofitions contained in the 
two firft Books of Newtons Trmctpia might per- 
haps be expreffed and demonftrated, without thofe 
various Meafures of Motion, and of centripetal and 
impreffed Forces which he ufes; But this would 
occafion fuch intricate and perplexed Circumlocu- 
tions, and fuch a tedious Length of Demonftrations 
as would fright any fober Perfon from attempting 
to read them. 
4 
Sect, 
