PARTIAL IMPACT.

Press, Volume LXVI, Issue 13714, 22 April 1910, Page 4

PARTIAL IMPACT.

TO THE EDITOR OF " THK FRKSS."

Sir, —The objection to tho proof of the dispersal of the Third Body, which was raised by Dr. Erans at last night's meeting of the Christctrarch Philosophical Society, can easily be met, and the statement made by Prof. Bickerton proved to be correct.

In the case of the complete collision of two bodies of given mass, moving with certain velocities at the moment of impact, it is evident that if the body resulting from the impact remains stationary the total energy is changed into heat, * The thermal units so generated a»*e distributed through the total amount of matter present in the Third Body, and give rise to a certain j rise of temperature.

In the case of partial impact of two exactly similar [todies, moving with identical velocities. If the resultant Third Body, consisting of one nth of each of the original bodies remains stationary, and the torn original bodies continue with their original velocities, it is evident that tho amount of energy transformed into heat is the difference between the total energy- of the two colliding bodies beI lore impact, and tho total energy of tho two torn bodies after impact; which difference can easily be proved to be equal to one nth of the original energy of the bodies: that is equal to one nth tl'c transformed energy on the case of complete collision. But these thermal units have only to be distributed through one nth of the total

mass, consequently the temperature of the Third Body in the ease of partial impact is equal to the temperature of the resultant body in the case of complete collision.

The question of the dispersal of the Third Body is onJy dependent on its own forces. In both cases the Third Body has a certain gravitational force; but ns tho law of gravity states that this force is directly proportional to the mass, it follows that the force of gravity in the case of tho Third Body, resulting from tho partial impact, is only one nth of the force of gravity in the body resulting from complete collision. The force tending to disperse the particles is the temperature, and is the same in both cases; consequently, if the body is in a state of equilibrium in tho case of complete collision, the resultant Third Body in tha case of partial impact must be dispersed by the greater force of its own heat. This, I think, meets Dr Evans' objection.—Yours, etc., R.C.H.

TO THE EDITOB OF "THE PKKBS."

Sir, —I should like to clear up a point left unfinished ot the close of the meeting on Wednesday. The theory of partial impact is amazingly wide; as Mr Laing, tbo chairman of the Philosophical Institute, said, "If all is true it is nothing less than a new cosmogony." But the point Professor Evans disputes is so apparently obvious that it absolutely amazed mc that a man of his scientific training could not see a factor that to mc is an absolute truism. I say if two cosmic bodies of different mass be equally heated, the smaller mass tends to be less stable than the larger. Supposing the earth and the sun were at the same temperature, such that, in each case the mean molecular velocity was o hundred miles a second, tho earth would explode and be dissipated into space, and the sun would remain a stable body. Astro-physicists say. that if a projectile were moving faster than seven miles a second; the earth could not retain it at all. It would leave the earth, never to return. On the other liahcl, in the case of the sun, a projectile requires to have on energy many times that of a hundred mjjea. a.. second.to completely escape ths;sun. Hence, at the temperature assumed, the earth would have more than a hundred times as much'energy as would produce a violent explosion, whilst the sun would simply go calmly on rejoicing in his comfortable warmth. It is extraordinary the oversights eminent men make in (studying work of a new type of thought, as evinced by the great Cuvier's treatment of Lamarck and hi 9 theory of evolution, of Tycho Bra he and -Copernicus, and more ■recently the treatment of Mendeal. So I suppose I ought not to have been so surprised at Dr. Evans os I was at this astro-physical overnight. But l>r. Evans is apparently on the wrong track altogether, as is suggested by his absolutely unsuitable analogies of a single pair of "men colliding in a set of ten pairs, and his illustrations of big and small red-hot iron balls. In the analogy of the iron balls he mixes up cohesion and gravitation.

I desire to thank Mr Hong for the very careful study he has given to the spectro-copy of the subject. Although generally I cannot acce.v-fc his conclusions, a part bein-**; based on tho idea that the expnnsion of tho ges shells is due to pressure instead of to Aheiilr molecular kinetic energy, yet I have to thank him for a suggestion that enabled mc at once to explain a ehoraot*?r of the blaze bands I had not studied. I desire also to thank' tlie Council of the Institute for the opportunity they granted mc of getting my views dobated.—Yours, etc.. A. W. BICKERTON.