SCIENTIFIC NOTES.

New Zealand Times, Volume XXIX, Issue 4253, 6 November 1874, Page 3

SCIENTIFIC NOTES.

Comets. —The length of the revolution of Coggia's comet has been estimated by Mr. Hind at 9000 years, but of course this will be modified when the observations in both hemispheres have been collected. Another new comet has been added to the list, and again the observatory atMarseilles is credited with the discovery. It will be known as Borrelly's, unless it should on further acquaintance be recognised as an old friend. Comet-lore is fast accumulating.- Astronomy is, indeed, just now the most progressive of the sciences. The "planotype" method of obtaining printing surfaces is described in Dingier's Journal. The design to be engraved is transferred to a block of lime-tree wood, which is then placed in a machine having somewhat the appearance of a sewing machine; but, instead of the needle, we find a steel pin (the shape of which varies according to the nature of the work), kept red-hot by a jet of gas. The design is thus gradually burnt into the wood. When the design has been completely executed, a stereotype is taken direct from the block, and is at once ready for printing. It is stated that the wood does not suffer from the heat of the molten metal, and that the finest detail maybe re-produced. TRANSFORMATIONS OF HYDROGEN.—MrLockyer, F.R.S., who has for a long time examined the sun and stars by means of the spectroscope, finds that in the spectrum of the hottest stars pure hydrogen only is to'hs detected. In stars which are less hot, the metals make their appearance.; in others again of lower temperature, the metalloids are found; and ultimately, here in our earth, which is an extinct star, free hydrogen is not to be met with, and the complexity of matter is remarkable. From this we may infer that if " dissociation," as chemists call it, could be carried tip to the last stage, we should find everything resolve itself into hydrogen. Some day we may perhaps be able to prove that all bodies are simply transformations of hydrogen, due to variable circumstances of pressure, temperature, and electricity. It is a question which must be left to the metallurgy of the future. Meanwhile, much may be done by increasing the temperatures with which we work. Bessemer with his steel-making process, and Siemens with his regenerating furnace, have led the way, and their successors will perhaps find a way to dissociate iron and oxygen, or iron and phosphorus. It all depends on the heat. The late Professor Faraday once said in a lecture,.that if hydrogen could be compressed and solidified, it would prove to be a metal.— Cfiamlers's Journal. " ■ Influence of Forf.sts on Climate.—The influence of forests on rainfall has ever been a matter of speculation and discussion. The popular notions are that the trees attract moisture from the soil, or act mechanically in causing the clouds which pass over them to give up their moisture. A much more reasonable conjecture is that the tree-roots open the soil to receive and conserve the rainfall, while the shade retards and regulates the evaporation. The soil never gets so much heated in a forest as in the open plain, and the moisture in the air is as a matter of course deposited on the cooler surface. The leaves are good radiators, and the prolonged evaporation generates electricity. The height of the trees above the plain, too, increases the rainfall. The difference between the wooded and the open surfaces are, however, so great, and the extent of the various influences so difficult of observation, that nothing short of actual observation in particular localities can be depended on for arriving at reliable results. It is but too true that such observations have not been made with so much sagacity as has been shown in the study of nature in its other aspects. The island of Barbadoes boasts of more complete observation of rainfall than can be obtained for any other locality of equal area. Scattered over the island there are rain gauges sufficient in number to allow of one for every square mile. A multiplicity of local causes'have thus been brought under observation, but it would be unsafe to jump to the conclusion that similar local features elsewhere would produce like results. Every country should yield its own crop of weather wisdom, and if good results are wanted adequate means must be taken, as in Barbadoes, to arrive at them. ' Scarcely anything of practical value has as yet been attempted in Victoria. A Wonderful Discovery Musrc by Telegraph.—Elieha Gray, of Chicago, well known in the electric telegraph world, has succeeded, almost beyond his own anticipation's, in perfecting an instrument which will convey sound by electricity over an unbroken current of extraordinary length without the aid of automatic repeaters. In the ordinary transmission of messages over telegraphic wires to points at long distances, a message is generally repeated by an automatic working instrument about every 500 miles, in order to renew the current of electricity. Mr. Gray has transmitted sounds which were distinctly audible at the receiving point, over an unbroken circuit of 2400 miles. It is one of the greatest discoveries made since the early days of Morse. Such noted electricians as George Prescott says it goes to prove what all electricians have long agreed upon, that we know little at present of the possibilities of the future of electric science. The writer has heard music played on a small melodian,' or piano key-board, transmitted through an unbroken circuit of 2400 miles, and reproduced on a violin attached to the receiving end of the wire. Mr. Gray played " Hail Columbia," "The Star Spangled Banner," "God Save the Queen," "Yankee Doodle," and other well known airs, and they were unmistakably repe'ated, note for note, on the violin, which lay on a table near at hand. Even an accidental false note was immediately detected on the violin. The apparatus, by means of which the feat is accomplished, has been named by Mr. Gray the telephone, or an instrument designed for the purposes of transmitting sound to a distance. It consists of three general parts, the transmitting instrument, the conducting wire, and the apparatus for receiving the sound at that distant point. The transmitting apparatus consists of a keyboard having a number of electro magnets correspondinh with the number of the keys on the board, to which are attached vibrating tongues or reeds, turned to a musical scale. Any one of these tongues can be separately set in motion by depressing the key corresponding to it. Thus a tune may be played by manipulating the keys in the same way as those of an ordinary piano or melodeon. The music, produced entirely by electricity, of these notes is so distinctly audible in the next room that, in spite of much talking, there is ho difficulty in determining what the manipulator is playing. — Alto California, July 25.