ORIGINAL CORRESPONDENCE. To the Editor of the "New Zealand Spectator." Wellington, May 21st, 1852.

New Zealand Spectator and Cook's Strait Guardian, Volume VIII, Issue 712, 29 May 1852, Page 2

ORIGINAL CORRESPONDENCE. To the Editor of the "New Zealand Spectator." Wellington, May 2 1st, 1852.

Sib, — As your valuable columns always present those subjects to the reader, which are the most interesthtgHihd useful, I, beg to offer a paper upon one which, although scientific, may perhaps be acceptable to many. The subject is that cf Heat, or, " The effects of Heat on the Mateiial World." If upon perusal you should deem the following article worthy of a place in your paper you will much oblige Your humble Servant, T. P. P. HEAT. . It is universally admitted, that, at one time of the earth's existence, it was iv a state of fusion, that is to say, it possessed so much heat that the' matter composing the earth's crust, at least, was either in the gaseous or liquid state. Now we know, from constant experience, that heat expands every substance thatTeceives it, consequent--ly the earth at the above period must have occupied a space inconceivably greater than itdoesat the present time. Let us picture to our mind a section of the earth being gradually heated ; those substances which have the least attraction of cohesion would change first, thus : air would liecome rarificd, water would take the form of air, and as the heat increased, iron, stones, diamonds, &c, would yield in order, till, _at last, the very hardest must give way. Let it be remembered that it is not those substance that possess the least specific gravity that would melt first; for iron has a less weight than lead, yet the latter .would melt first. - Having got the world in tbis state of fusion let us

imagine an opposite process, namely, tliat of cooling by radiation. In this there would be the same order as in melting, only those substances which have the greatest attraction of cohesion, or, which melted last, will harden 6rst. Now what, ever substance would consolidate prior to all the rfst, must leave the others by contracting and occupying a central position, wl-ile the next in consolidation would form the first layer by gradually concentrating. And in this way every elerrent, o* compound, which assumed the solid >state under the greatest remaining heat, would .become a layer upon its predecessor. Suppose all the layers to have taken their respective places until water and air formed the first two. This would be a dreary spectacle and at best only an habitation for fishes, even if the water were •cold enough ; for it must be remembered that it would be like a casting in the sand which, although solid very soon, yet continues red-hot for sometime. Such would really he the case with the «arth and it must be confessed that the central parts would remain intensly heated for a long time : each additional layer w< uld impede the radiation of its predecessor, and to this day the deeper we can descend into the earth the warmer we find it. Hut this is not all ; let us walch the •conduct of the several layers now that they have taken their places: ever since the time that the mighty structure of the earth was completed, the same agent which both deposited the found ition and raised the superstructure, has been influencing the mighty fabric, radiation of heat ■continues, loss of heat implies contraction, and the contracting layers are ever and anon disturbing those that lie above them and which have long since done shrinking. Let us imagine what would be the probable result of this tendency of •cooling matter, at a period when it must have been very act've in consequence of the great radiation. As there are some substances which -expand more than others under the same heat, it follows that they will shrink the most upon cooling. Now if the thirtieth layer of the earth's «rusf, counting from the surface, was expanded more than the twenty-ninth under the s-iiine beat, there would, upon cooling either be a vacancy formed between the two, or else the outermost would be broken and forced through the superincumbent part of the crust at the place of fracture, forming mountain chains, and in the midst of these the fiery channels which we call volcanoes. Instead however, of allowing different degrees of ■contraction under the same heat to be the cause of mountains we might allege that as those parts -of the carth 1 * crus.t near the surface are much colder than towards the cant re, the foimer would -finish contracting comparatively early and in •couise of time might be forced upwards in different parts by the shrinking of the latter.