Page:Passages from the Life of a Philosopher.djvu/487

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CAUSES OF MAGNETIC CHANGES.
471

On considering the whole question, I arrived at the conclusion, that to conduct the affair to a successful issue it would occupy so much of my own time to contrive and execute the machinery, and then to superintend the working out of the plan, that even if successful in point of pecuniary profit, it would be too late to avail myself of the money thus acquired to complete the Analytical Engine.


Problem of the Three Magnetic Bodies.

The problem of the three bodies, which has cost such unwearied labour to so many of the highest intellects of this and the past age, is simple compared with another which is opening upon us. We now possess a very extensive series of well-recorded observations of the positions of the magnetic needle, in various parts of our globe, during about thirty years.

Certain periods of changes of about ten or eleven years are said to be indicated as connected with changes in the amount of solar spots; but the inductive evidence scarcely rests upon three periods, and it seems more probable that these effects arise from some common cause.

(1.) It has been long known that the earth has at least two if not more magnetic poles.
(2.) It is probable, therefore, that the sun and moon also have several magnetic poles.
(3.) In 1826 I proved that when a magnet is brought into proximity to a piece of matter capable of becoming magnetic, the magnetism communicated by it requires time for its full development in the body magnetized. Also that when the influence of the magnet is removed, the magnetized body requires time to regain its former state.