PLANETARY GRAVITATION 



stices of all bodies, however great, and must, therefore, 

 in part only, pass through them, doubtlessly in some 

 definite though unknown ratio. The Ethereal molec- 

 ules would lose their motion in direct proportion to 

 the number and nature of the molecules in the mass 

 that absorbed their motion, being changed partly into 

 molecular motion of the respective molecules, which 

 are known to be in an actual state of vibratory mo- 

 tion, and partly are changed into the translatory mo- 

 tion of the mass of the planets ; which motions, from 

 being naturally tangents to their orbits, are forced at 

 right angles thereto into the curves of their ellipses. 

 The impulsive action of the ethereal atoms would 

 therefore diminish in the ratio that the respective 

 masses of ponderable molecules absorbed their motion 

 not be kept off as rain-drops would be by an um- 

 brella. 



The difficulty of accounting for the origin and 

 maintenance of the inherent motion of the atoms of 

 the Ether in their free path is as great as in account- 

 ing for the vibratory motion of the atoms of solid, 

 liquid or gaseous matter, but not greater. It is the 

 question concerning the First Cause ! To this quest- 

 ion human intelligence can give no definite answer. 

 It should be remembered, though, that it is more 

 philosophical to assume that the Ether which pervades 

 the universe, extending far beyond those regions from 



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