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The Mode of Action of the Gravitory Force.

A leading writer on astronomical subjects, says that though nearly equally divided, the balance of opinion slightly inclines in favour of the force of gravity acting simply as a property of matter, and that no agent is intermediately concerned in drawing one mass of matter towards another. Any theory that might have formed, seems to have been of value only in a negative sense, in that it was less objectionable than some other. If the way in which the force of gravity must act be considered, many great difficulties will present themselves.

If that power which causes bodies to gravitate be exercised through the medium of a current, then a current must be conceived to flow from an indefinite distance outside a body, and towards the centre of that body. This current, of course, becomes more condensed as it approaches the centre, and this would be in agreement with the facts of the gravitory force.

The motion of a current in itself would be a sufficient cause in carrying one body towards another. Several instances, however, present themselves to the mind which render the supposition that the force of gravity is a current impossible, or almost impossible. In considering the mutual gravitation of the earth and moon, a current would have to be conceived flowing towards the centre of the moon, carrying the earth with it; and at the same time there must be conceived a contrary, and consequently opposing current, flowing towards the centre of the earth and carrying the moon with it. The currents oppose each other, and the supposition, therefore, is opposed to reason.

Though, however, gravitation is not the effect of a current, yet, if a single current only were to act it would give a partially satisfactory explanation of gravitation. Whatever agent or medium causes gravitation must do the work of a current, but must remain in the same place. It must, therefore, have a peculiar (perhaps a kind of vortical) motion of an intensely rapid kind. The motion might be of an endless screw character. In any case in its effect it must act upon matter, as the webbed foot of a swimming bird acts upon the water.

Though not a current, the force of gravity acts like one. For the sake of simplicity it would be well to suppose that it is a current. If a plank is pushed endways against a stream of water, it can be so pushed without any great labour. It would be a matter of greater difficulty to hold the plank transverse to and against the stream when its edge was presented. If the plank were held transverse with its face against the current, the difficulty of holding it would be very much greater. If, however, the plank is held against the force of gravity, imagined as a current, it will make no difference whether the plank is held end, edge, or face up. That is, the power required to maintain the plank against a current of water is very different in three cases; but, to sustain the plank against the imagined current of gravity, exactly the same power appreciably is required in the three cases. A little consideration would show clearly that only the outside of the plank was acted upon by the current of water, while the supposed page 8 current of gravity must act on every particle of the plank. The current of gravity must then flow through the solid as water flows through a sieve. As an illustration of the principle of the action of gravity, the case may be taken of a ship in which the sails are not made of canvas, but of a kind of netting. The wind rushes through these sails of netting, but the ship is driven forward nevertheless. That the force of gravity (if a current power) acts upon matter as the wind acts in the foregoing case on every thread of the sails, will be considered possible or even necessary.

At the surface of the earth, the velocity produced by the force of gravity is, at the end of one second, 82.2 feet; at the end of three seconds, 96.6 feet, &c. The question now arises, whether there is any limit to this velocity. This point has not perhaps been directly tested, and it cannot be easily answered. The ultimate velocity that could be produced by the gravitory force of the sun is reckoned to be 400 miles per second. Another question also arises. Will a mass, say, of iron weigh as much as the same volume and density when cut into many small pieces? No experiments have probably been made on this point either. Another point presents more difficulties. The motion of the gravitory fluid within the mass having been lessened, the more rapidly moving, or gravitory matter, outside the mass, presses inwards to restore equality of motion; but whether the slower moving is driven out of the mass, or excited to almost equal activity, is difficult to determine. This is a most important point in considering the action of the gravitory fluid among the particles of a solid so vast as that of a planet.

Some possible results are: that the motion of particles of gravitory matter is greatly destroyed, and that the particles of a solid are put into motion to some slight extent.

The conception of what an element of matter might be is most important. This element of matter has to satisfy so many conditions that it is difficult to conceive it.

Perhaps the element described in the following lines would satisfy many of the conditions which have to be fulfilled:—It may be considered as having the form of a life-buoy, with the opening or inner circumference, however, narrowed down to almost nothing. The tubular portion must be considered as a hollow shell—a thin elastic tubular film. The tube must be considered as revolving within itself, so to speak, the inner part having a motion upwards, and the outer a motion downwards. To aid the imagination, this tube may be supposed to consist of very elastic rings laterally compressible, and expansible in a very high degree. They can be considered as gummed together at their edges. If, now, a tight-fitting rod is pushed up through the opening or inner circle of this tubular series of rings, all the rings of which the tube is composed will of course revolve—the inner part of their circumference moving upwards, and the "outer parts of their circumference moving downwards. The general outward form of this element may be supposed to be nearly spherical. It may be likened to a slightly- page 9 flattened orange, with a small cylindrical portion cut out around the vertical diameter, the top and bottom of which tube would be slightly funnel-shaped. The motion would then be the same as if the rind of the orange moved downwards, ascended through the funnel-shaped tube, and so kept circulating. In any space these elements would occupy positions similar to those occupied by equal-sized oranges packed in a box. Their axial diameters are supposed to be vertical. It should then be remembered that all the outsides of these oranges have a motion downwards, the ascending motion taking place through the opening cut around what might be called their polar diameter. A little consideration will now show that all these elements exert a mutual pressure; that they always set their polar diameter perpendicular to a flat surface; that the contiguous elements adjust themselves; that any inert substance is carried downwards; that an element of slower motion is carried down wards, while an element with quicker motion will raise itself upwards, and that they will possess other powers or properties besides.