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ANNUAL ADDRESS . 
The Simplification of First Principles in Physical Science. 
Ladies and Gentlemen, 
Haying recently been requested to address you on the 
present occasion, I wish it had been in my power to have 
thrown my observations together in a more satisfactory form 
than that in which they are now presented. The subject on 
which I propose to address you is “ the Simplification of 
First Principles in Physical Science, as an evidence of the 
unity and comprehensiveness of Creative Wisdom/ ' There are 
no recent facts or investigations connected with physical 
science in which that has taken place so conspicuously as in the 
establishment of the principle of the conservation of energy, 
and the correlation of its physical modes or forms. On this 
subject a very suggestive treatise has been written by Mr. 
Grove, and upon that treatise some excellent observations 
were made in a paper addressed to this Society some time 
since by Professor Kirk. Some of the observations he made 
with regard to the inconclusiveness and want of logical accu- 
racy in some of the arguments adduced in that treatise, sprung 
out of the indefinite use of terms by Mr. Grove. It is upon 
that subject that I should like to offer you a few remarks. The 
title of Mr. Grove's treatise is “ The Correlation of Physical 
Forces," and what has been frequently mentioned as “ the 
conservation of force ; " but I prefer to reject the latter term, 
and to speak of the conservation of energy, and the correla- 
tion of its physical modes and forms. The term “ force ” is 
not an applicable term, because it is not definite. It is a term 
which has been applied to several distinct things. It is applied 
to that to which I would limit it, and also to that which force 
produces, namely, energy ; and it has also been applied to the 
mere non-existence, or negation of energy, or what in former 
times was called the vis inertice , which was the supposed 
positive existence of the power in a body to remain at rest. 
But that evidently is no force at all : it is simply the non- 
existence of any form of energy by which any portion of 
matter may be put in motion. Both force and energy may 
