KINETIC THEORIES OF GRAVITATION'. 245 



the distance is infinite, the integral is negatively infinite. But how it 

 is a function of " space" in any more general sense, is certainly not ob- 

 vious. As Professor Briieke, of Vienna, has forcibly said in his response 

 to Faraday : " So far as my consciousness reaches, so far as I am capa- 

 ble of distinguishing true from false, and like from an Like, all known 

 facts are brought into complete harmony with our laws of thought, 

 when we suppose forces as the causes of phenomena to reside in the 

 masses, the spaces between these masses being traversed by the forces. 

 If the forces could be imagined as existing in space, it must also be 

 conceivable that matter may be annihilated without changiug the sum 

 of the forces, and this, at least by me, is not conceivable/'* 



" Section li. The force-generating faculty exists in space, and is di- 

 rected centripetally. [?] This is proved by the following considerations. 

 The integral force-producing power of any body, however small, subject 

 to the law of universal gravitation, is illimitable as space. It is impos- 

 sible to imagine an infinite attribute belonging to a finite entity .f It is 

 therefore in space that the energy that contributes the power of gravi- 

 tation exists, and the element of matter merely gives to it a centripetal 

 direction. This, as a consequent of the law of gravitation, seems note- 

 worthy from it probably being applicable to molecular forces generally. 

 It favors the idea that the function of the material element is to give 

 direction to a liviug force that pervades space.'"! The first part of this 

 proposition, (as an iteration of the previous one,) that gravitative force 

 "exists in space," is derived as an infereucefrom a metaphysical postu- 

 late, — "It is impossible to imagine" it as belonging to a finite bod v. 

 But our powers of " imagining" can hardly be accepted as the measure 

 of scientific verity. "It is impossible to imagine" the nature of elec- 

 trical action, chemical affinity, lumini"erous vibration, rether, atom, 

 force, or space ! Who is able to formulate in thought the co-existence 

 of an equal repulsive and attractive energy in either pole of a bar 

 magnet, simultaneously discriminating by opposite action between the 

 reversed ends of two magnetic needles? But when it is said that the 

 sole function of the material element is to give centripetal direction to 

 the circumambient ocean of force, wonderful indeed is the conception of 

 virtue in the u finite entity" thus drawing to itself the centripetal ten- 

 dency in all directions throughout illimitab'e space, and instantaneously 

 re-adjusting these infinite lines of force with every momentary change 

 of position ! If difficulty of "imagining" were a criterion of error, 

 surely it might be well applied to this hypothesis. 



" Section 3. The law of gravitation with respect to the element of 

 radial space, is usually defined with reference to a constant element of 

 time; the increment of velocity generated being proportional to the 

 increment of time, whatever the direction or velocity of the motion, and 



* L. E. D. Phil. Mas., February, 1858, vol. xv, pp. 87, 88. 



t Is it impossible to imagine an atom having an eternal duration ? 



i Pbil Mag., 1858, vol. xv, pp. 331, 332. 



