tricity and that electricity is the light and caloric that stream from the sun. The attraction of gravitation, then, is the attraction of terrestrial magnetism.

It has been the current opinion, among the mass of the community, and even among scholars, that every thing is attracted towards the centre of the earth, as though that possessed some mysterious, unaccountable power of attraction over substances, (somewhat akin to the unphilosophical opinion, that the north pole star guides the needle of the compass,) and that it increased all the way to that centre. But such is, by no means the case. The attraction of gravitation, instead of being the greatest at the centre, is the greatest at the surface of the earth.

Were it possible, for instance, to perforate through the earth, exactly at the magnetic centre, instead of the geographic, a substance, which might weigh hundreds of tons at the surface, would weigh just nothing at all at the centre. It would be suspended there, were the space large enough, without any apparent support, like a light needle, when suspended within a helix, or coil of insulated copper wire, while passing a current of galvanism around it. And why would this be the case? Because the electrical or magnetic attraction would be equal on all sides of the centre of the earth, and, therefore, a substance, which would weigh several tons at the surface, would there be perfectly balanced, without support, and would, in that position, weigh just nothing at all, since all weight depends upon attraction, and that weight is exactly pro

portional to the attraction. As the power of the attraction is equal on all sides of the centre of the earth, and, as attraction one way, without a corresponding attraction the other, causes all weight, therefore, a substance at this centre, must weigh nothing, because the attraction being in all directions equal, must be neutralized.

The attraction of gravitation, or, in other words, the attraction of terrestrial magnetism, which is the same thing precisely, is the greatest at the surface of the earth. It may be asked, then,-" Why do all falling bodies, fall toward the centre?" Simply because the radiations of magnetism obey the same law, precisely, as the radiations of light. The lines of these radii if continued on within the surface, or through

the earth, from one side to the other, would intersect the centre, and the attractions of the surface are, therefore, directly toward the centre.

From the fact that the radiations of magnetism, obey the law of the radiations of solar light, and all other light,—that is, from the fact that the divergence of the radiations of magnetism is in the exact proportion of the squares of the distance, the same as the divergence of light, gravitation, therefore, attracts all bodies around it, in proportion to the squares of the distance of those bodies. So that the organic laws of magnetism, light and gravitation are the same, and, like laws produce like effects as well as like causes.

Before dismissing the interesting subject of gravitation, we would express our belief, that it is a proposition capable of demonstration, that an increase of the material of the earth, would increase its attraction in precisely the ratio of the increase of the attraction of the magnet, by the increase of its material. Were the material of the earth doubled, for instance, its attraction would be quadrupled, precisely in accordance with the law of the divergence of light, or the radiations of electricity. Consequently the weight of all bodies upon its surface, of the same bulk and density, would, in such a supposed contingency, be quadrupled in accordance with an immutable law.

Now, from all that has been said, does it not appear perfectly evident, that gravitation has a cause, as definite and as easily explained, as magnetism; which cause is precisely the same. The great magnet of Professor Henry, for instance, to which we have already alluded, would, when fully charged with the galvanic current, neutralize all the power of the earth's gravitation, and make a body gravitate upwards from the earth, with a power equal to two or three tons.— And why? Simply because a vast volume of electricity was accumulated there in a small compass, by means of the insulated copper wires, around which the galvanic fluid circulated. Electricity or light, then, we can legitimately conclude, is the cause of gravitation.

LECTURE X.

THE CAUSES OF MAGNETIC ATTRACTION, THE AURORAE, GRAVITATION, COHESION, AND THE MOTION OF PLANETS DEMONSTRATED BY A VARIETY OF ARGUMENTS, TO BE ELECTRIC AND IDENTICAL.

The attraction of cohesion has the same cause, as the attraction of gravitation. They are both doubtless, produced by that electric cause, the light and caloric of the sun. The one is the attraction between large masses, and the other between the component particles of those masses, the one attracts at great distances, and the other at insensible distances-their attractions are, therefore, the same in essence, though not in volume or degree. What holds the armature of Henry's large magnet, when charged, but the simple power of cohesive attraction between the particles of the iron, which composes the material of the magnet and armature, which cohesive power is caused by electricity? We believe it is nothing else. The same power, precisely, holds the particles of all bodies together, and that power of cohesive attraction varies often as the amount of latent caloric varies. Abstract the latent caloric of iron, for instance, by intense cold, or by any other cause, and you, in a proportionable degree, destroy its cohesive attraction, and

make it brittle. This is proven by the ease with which iron is fractured, in the intense cold of the win

ter.

By hammering iron when cold, or by rolling it in a rolling mill, it will also become brittle. And why? Because the caloric, which constitutes cohesive attraction, is pressed out upon the surface, by closing the pores. This is proven by the fact that caloric accumulates upon the surface, in proportion as the pores of the iron are contracted by the rolling mill or the hammer, which drive out the latent caloric.

The various phenomena of capillary attraction can be referred to the same cause, as cohesion to the caloric, that electrifies all substances under its influence. The tallow that composes the candle, for instance, is drawn up into the wick, during combustion, by capillary attraction, and that attraction is caused by the caloric set free during ignition.

We are well aware that many objections to the validity of our positions can be started by fruitful imaginations, which may appear plausible and seem to conflict with the conclusions which we have drawn, but which must be deceptive, since the laws of nature do not clash, and, if some of the reasons, and the modes of her operations are beyond the ken of the acutest and most penetrating scrutiny, it amounts to no conclusive proof that we are incorrect. The question is simply this. Have our deductions appeared rational, and in accordance with known and tested laws, and have they been amply sustained by an accumulation