Polytechnic Association Proceedings. 933 



the truths shown are sufficient for the effect — the effect is purely 

 mechanical and plain to the sense; in harmony with the mechanism 

 of the heavens and the order of revolution, and, until a better 

 reason is shown, I am compelled to believe in its entire truth.* 



The cause of gravity has never yet been explained or understood, 

 notwithstanding that much is known of the 1-aws which regulate it. 

 Newton discovered that a falling body was governed by certain 

 laws, and that these laws were applicable to the motions of the 

 heavenly bodies, and this he called gravity, or the " attraction of 

 gravitation." But neither he nor any one else, that I am aware of, 

 ever explained in any satisfactory manner, even to himself, the 

 cause of this gravity. But if my positions be true, it will appear 

 that one law governs polar attraction, centripetal force and the 

 gravitation of bodies, viz: a latent magnetism set at liberty, 

 rendered active, and involved by a forward revolution. 



The earth* attracts all bodies to its center, and a stone, because 

 of its greater density, will fall quicker through the atmosphere 

 than a feather; but I regard density as only an element of velocity 

 in overcoming the resistance of a medium, and the atmosphere 

 being withdrawn, the feather, attracted by the magnetic force, will 

 fall as quick as a stone.f 



• In limiting the period of the revolution to six hundred and forty years or thereabouts, 

 it will be observed that the correctness of that period depends entirely on the accuracy of 

 the observations and record of the variations of the needle from time to time. And as a 

 consequence of the sensitiveness of the needle to diverting causes from local attraction, 

 and the slowness of the motion, which renders it difficult to note the exact period of ita 

 passage of any particular meridian, together with the probable imperfection of the instru- 

 ments in early use for observation, on which the records depend, even if all we have here 

 said be perfectly true in principle, the actual period when found may prove to be somewhat 

 longer or shorter than the period here named. Astronomers have suggested an indefinite 

 period of six or seven hundred years, which I have sometimes seen mentioned, and which 

 marks an epoch with thom. They may, perhaps, find little difficulty in harmonizing it 

 with this revolution. 



\ The subtilty and force of magnetism was illustrated by Laplace under the name of 

 gravitation. He says, "that if a new planet were thrown into space, it would instantly 

 feel the force of attraction from surrounding bodies whatever their distance, and the 

 velocity of that force, from one body to the other, would be many million times greater 

 than that of light;" but I am not aware that he ever associated magnetism with gravita- 

 tion, or treated of it as a universal principle and an active force in nature. Certainly he 

 never considered the two as identical. Most of the inquiries of scientific men into the 

 principles of magnetism have, as I believe, been expended in experiments on magnets, 

 instead of magnetism. I can very well believe Laplace as to the velocity of magnetic 

 attraction. We have an example of velocity in the Atlantic cable. The electric influence 

 is oomputed to have passed over a distance of two thousand miles in six- tenths of a second, 

 but even that time was probably employed by the thought of the observer in marking the 

 time, and the electric current passed in no appreciable space of time. 



