25‘i 
Cases of diffi 
ciilty in tlie 
doctrines of 
moving force 
MOVING rORCK. 
That great misunderstandings respecting the subject under 
consideration, have arisen from the various senses in which 
• the terms have been taken, must be acknowledged. But it 
cannot, I think, be reasonablj' contended, that the whole has 
been merely a dispute about w’ords. 
Soon after it had been shown by Huygens, that the ascen- 
sional force of a body in motion is as the square of its velocity, 
that principle was extended and brought forward in a manner 
very unfavourable to its general reception. It was adduced by 
Leibnitz* as an argument against Des Cartes ; and afterwards 
by Bernoulli and othersf, as a principle which must supplant 
or supersede some of the leading doctrines of the Newtonian 
philosophy. Great opposition was naturally excited by these 
last pretensions ; and, as it is invariably the case in intempe- 
rate controversies, the advocates on both sides were led into 
many inconsistencies. It soon became quite a party question, 
and the prejudices against oije side became so strong, that if 
any one ventured to consider the absolute force of a body in 
motion to be as the square of its velocity, he was pitied or con- 
demned as if he had lapsed info a dangerous heresy. It is to be 
regretted, that these prejudices, if such they are, are not yet 
entirely removed. For myself, I must acknowledge, that it is 
a matter of some concern to me, that, in consequence of the 
explanations which I have thought it necessary to adopt in en- 
deavouring to understand this subject, I have, by some of my 
very good mathematical friends, whose favourable disposition 
it is my wish to conciliate, been considered more in the light of 
a perverse schismatic than in that of a patient enquirer j and 
I intreat that the two great length of this, 1 fear tedious, dis- 
cussion may be ascribed to my desire to merit the latter rathef 
than the former appellation. 
I cannot help thinking, that if this rejected principle had 
been first produced, not in opposition to, but as, what I believe 
it really is, an extension of the Newtonian doctrine of force^ 
* Act. Enid. Lipsae, 1686, p. 161. 
t Works, vol. iii. 
it 
