[ 47 ] 
eminent Mathematicians of the laft and prefent Age; 
as Dr. Hook , Mr. John Bernouilli , M. Camus , &c. 
But, as all that I have yet fcen upon this Subject 
goes no further, than to compare the Effe&s of dif- 
ferent Springs one with another, without (hewing 
how the EfFed of any of them may be reduced to, 
or compared with, that of any other natural Caufe, I 
flatter myfelf, that the general Proportion 1 am going 
to lay down may merit your Attention, both on 
account of its Simplicity, and of its comprehending 
all poflible Cafes of a Body acting upon a Spring, 
or a Spring upon a Body, where no other Power 
intervenes ; and alfo of its reducing the Effed to that 
mold known and fimple one, the Effed of Gravity 
upon falling Bodies. 
In order to which, to prevent any Mifapprchenfion, 
it will be proper to fix the Meaning of fuch Terms as 
Ifhall have Occafion to make ufe of. 
1. By a Spring, 1 mean a Body of any Shape per- 
fectly eiaftic. 
2. By the natural Situation of a Spring, I mean 
the Situation it will reft in, when not difturbed by 
any external Force. 
3. By the Length of a Spring, I mean the greateft 
Length, through which it can be forced inwards. 
This would be the whole Length, were the Spring 
confidercd os a mathematical Line; but in a material 
Spring is the Difference between the whole Length 
when the Spring is in its natural Situation, and the 
Length or Space it takes up when wholly compreffed 
or clofed. 
4. By the Strength of a Spring, I mean the lead: 
Force or Weight, which, when the Spring is wholly 
comprefled- 
