To the Editor of the "New Zealand Spectator." Wellington, July 30, 1852.

New Zealand Spectator and Cook's Strait Guardian, Volume VIII, Issue 730, 31 July 1852, Page 2

To the Editor of the " New Zealand Spectator." Wellington, July 30, 1852.

Sir, — Having been favoured, a short time since, by the appearance, in your interesting columns, of an article on heat, I have been induced to ask the like favour with regard to another on " the motion and distances of the planets." I am, Sir, w Your humble servanf, Thomas Purseglove. I suppose there are but few people who have , not at some time or other either been spinners of tops or observers of the motions of these beautiful toys. These, together with the spinning of .coins upon a smooth surface, have of late so occupied my attenliou, that a number of experiments have been the result ; and the conclusions drawn from these are, that either a top or a coin when spinning is a perfect illustration of the annual and diurnal motions of the planets. No one ever saw either the one or the other move forward in a straight line while revolving upon its axis. It is as unnatural for, one of these, while spinning, to move forward in a straight line, as it is for a body which does not revolve upon a centre to move forward in a circle. If, therefore, any body revolves upon an axis as the planets do, and at the same time possess an onward motion, sucb onward motion must be in a circle, and the axisupon which they Tevolve will be perpendicular to (he plane they circumscribe. But besides this, these two motions have a relation to each other ; for as tl-e motion upon the axis decreases, the onward motion increases, v)\\]e the circle circumscribed decreases also. No one need remain ignorant of the truth of these statements — a penny and a smooth table are always attainable. If we look to the motions of the planets, we shall find that the less the motion upon the axis, the greater the motion in the orbit, while the orbit itself is a smaller circle. Now, if it be natural ior the planets to move forward in a circle because they revolve upon their axes, they can have no tendency to fly from their orbits by centrifugal force, and therefore they can render no opposition 1 to the attraction of the sun, and consequently this power has nothing to do with the annual motions of the planets. If there be therefore such a thing as attraction, there must also be a power of repu'sion to neutralize ils effects, so that whether the planets be stationary, or whether they move in an orbit, they must be enabled to maintain their respective positions with regard to their distances from the sun. Let us now see what this repulsion principle is. If a piece of matter of any' kind be heated, the atoms which compose it are forced from each other, so that when they are the most heated they are the most distant. This increased distance causes an increased bulk in the heated mass, but with this additional bulk there is no addition in weight : this is therefore a' decreased specific gravity with an increasedjieat, and the specific gravity is gradually increased* iv the process of cooling. Now it is known that the planets decrease in specific gravity as their distance from the sun increases ; Mercury, which is the nearest, having the greatest, while Herschel, the most distant, has the least. This not only shows that the greater the distance the more intense the heat, but also that this distance depends upon the heat ; and that the various positions of the planets are at points where their respective heats are equal to the attraction at such places. No one scarcely doubts that our earth has been in a. highly heated state, and it has been often thought that the sun himself was a burning mass (which is almost certain, as his specific gravity is less than that of any.of the planets ;) it appears also that every planet in the system has not only been heated to the 'greatest intenstfflfijwt that comets with their fiery trains are but^^plts in infancy, and will sooner or later take their stand as orderly attendants on the sun ; while the. p] a nets themselves, by gradually losing their beat, are permitted to come nearer and nearer to their common centre. It is probable that those planets that are nearer the sun than we are have lost so much of their latent heat ; that were it not for the sun's rays every particle of vegetation upon them would be destroyed ; and that every drop of water, if not eveu the air itself, must be reduced to solidityThe more distant planets may have most of their hard matter in a, state of fusion even yet, whiie the* water Is but condensing into visible steam.

Kawhia. — On Monday, the 7th June, an accident happened to the native postman, in crossing this harbour, which had well .nigh been* fatal to-him and caused the loss of the mail. The wind was strong, and the weather stormy. He was disappointed of an expected passage in the boat of one of the settlers, who was always kindly ready to accommodate the mailmen, f and, with a canoe and sail, attempted the passage. He had got two-thirds of the distance, when a sea "filled his canoe and turned her over. He dexterously secured the mail-bag, and even two, loose letters he saved by holding them between his teeth. He got on the bottom of the canoe,

and, after throwing away his garments, with one hand he grasped the hag and with the other he swam to t;he shore. Almost perished with cold, and nearly exhausted, he managed to get along the beach to the houses of the settlers, where he was kindly attended to — and, after obtaining clothing from them, and'recovering from the effects of his disaster, he pursued his journey to Auckland, where he arrived with the mail, on Saturday, the 12th June Jt is to be hoped that the gallantry of his conduct in thus saving the mail at the risk of his life, and at the sacrifice of his clothes, which were his all, will not go unrewarded This is the first accident that has happened to the native postman since the commencement of the overland mail, more than eight years ago, al though they have to travel in all seasons ot the y-ar, in all sorts of weather, and often in canoes, in crossing rivers and harbours, anything but safe. — Communicated to the New Zealander, July 7.