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Essay on Motion and Force. 



ogy leads us to believe, that, as before enunciated, if a 

 body near to the earth moves more than at a distance 

 from it, some other matter or body of matter must move 

 less, and thus the great doctrine of the conservation of 

 force is not affected. 



This doctrine of the conservation of force is, I believe, 

 accepted by the leading naturalists of the present day 

 almost universally. But if it be true that all the so called 

 forces of which we are cognizant, are to be considered as 

 modes of motion, the term, conservation of force, should 

 be altered to suit this view, and the term, so altered to 

 conservation of motion, would inevitably and logically 

 lead us to these propositions : First, the amount of motion 

 throughout the entire universe is constant for all times, 

 and for any particular period of time ; and, secondly, 

 when any particular motion ceases, partially or entirely, 

 some equal amount of motion takes place simultaneously. 

 In other words, the cessation of any particular motion 

 of matter is either a proximate or a remote cause of motion 

 in other matter. I do not propose to discuss the ques- 

 tion of the simultaneity of cause and effect, although, 

 of course, this has a most important bearing upon 

 he doctrine of the conservation of motion ; but I will 

 simply remark in passing, that the theory of the 

 conservation of motion, so far as material causes and effects 

 are concerned, throws a clear light upon this much debated 

 question, and completely confutes the old dogma of the 

 logicians: " Cessante causa cessat et affectus for a motion 

 which takes place upon the cessation of another motion, will 

 continue until itself becomes the cause of still another 

 motion, a fact now admitted by all, except in those cases 

 in which the motion seems to disappear ; as in the case of 

 bodies coming to rest upon the earth's surface after falling, 

 or the arresting the fall of a body by the tension of a spring 

 or cord. 



To account for the supposed suspension of motion in 

 such cases, the idea of an occult force or power, existing in 



