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Otago Witness, Issue 2402, 15 March 1900, Page 58

SCIENCE NOTES.

— Many dwellers in the country who are debarred the luxury of gas will hail with pleasure the advent of a new lamp, capable of rivalling the incandescent gas-burner, but without the need for gas. Such a lamp has been devised by M. Denayrouae, and was recently exhibited before the French Society of Civil Engineers. The light of an ordinary fishtail burner is due to the incandescence of particles of carbon reduced from the coal gas by the act of combustion, and rendered white hot by the heat thereby evolved. According to St. Claire-Deville, there is only about from 3 to 6 per cent, of carbon in coal gas, the surplus hydrogen being able to raise to white heat a far larger proportion than this if it were present. This fact is made use of in the Welsbach burner, which, from a given amount of gas, produces about five times more illumination than if burnt in an ordinary fishtail or batVwing, or even an Argand, burner. Many burners have been devised to cause an incandescent illumination from alcohol or petroleum, etc., as the combustible, but, so far, with little practical success. M. Denayrouze has hit upon a combination of the two systems. He uses alcohol to which a hydrocarbon has been added; in heating the mantle carbon is deposited upon it, and, along with the mantle itself, is rendered incandescent, and thus a double source of light is provided. The lamp was a success; but the inventor kept to himself all details as to what form of carburetling aocnt was supplied. It is probable that an"* invention of such value will be taken up by the manufacturers and placed upon the market if, in-its present shape, it is a really practical lamp.— British Journal of Photography. —It will be remembered that during the great' naval display which formed such a notable feature of the Jubilee year, a certain vessel called the Turbinia— f rom the fact that the engines which turn hei propellers are .of turbine form — made a sensational run, for the edification of the visitors, at a speed approaching that of an express railway train. The principle has been adopted in a torpedo-boat destroyer which has recently been constructed for our navy by Messrs Armstrong and Co. at Elswick; and a Newcastle correspondent of the Shipping Gazette gives a remarkablo account of the behaviour o£ the vessel during

her trial trip. Scarcely bigger 'than one of the ordinary destroyers, she tears through the water, leaving in her wake "a wall of whiteboiling water." At full speed she gave the impression of flying over the waves without effort. "I saw her," says the correspondent, "run out of sight to the north in 20 minutes, and reappear again sfcepming south in 10 minutes, and I watched her turn completely round so quickly that the eye was deceived in the movement."

— One of the most gratifying evidences of the progress of Mexico during recent years has been the constantly-increa°ing importation of labour-saving machinery. Ihe total importation of machinery during the year ended June 30, 1897, amounted to £751,000, while during the next fiscal year it was £1,088,000, New manufacturing plants of almost every description are being built all over the Republic. la no country in the world ai*e cotton mills pa;/ing such large dividends on the capital invested, and the magnificent water-pen er facilities, unused for centuries, are now being utilised. Immense mills were constiucted only last year at the falls of Juanacatlan, near Guadalajara. Besides all kinds of cotton goods, Mexico to-day manufacturers a very good quality of oassimeres and woollen goods, blankets, stockings, knit underwear, shoes, and all kinds of leather goods, and hats of wool, fur, and straw, blocked in' the modern and prevailing style of the country. She is also beginning to make linen and silk fabrics, a determined and somewhat successful effort being made at present to raise the silkvrorm in the Slate of Guanajuato. Sugar and alcohol ore also manufactured. The establishment of these new enterprises, fostered by the protective policy of the Government, is giving an impetus to every industry, and offers to the roawufaoturer of machinery^a most inviting field. Arrangements should be made to allow as long credits as possible, for, in almost every instance, excellent security will be tendered. The busineos should be entrusted to men thoroughly conversant with the language, and well acquainted with the peculiar customs, of the inhabitants and the agricultural requirements of the country. The machinery introduced should be carefully explained to the native farmer. The Mexican is conservative, and when an instrument or tool has been accepted, it is difficult to convince him that another is more meritorious ; thus, for the tmall amount of extra expense to which the manufacturer has been subjected in introducing his waice, he will be doubly compensated in the future extension of his export trade. Another source of profit to the machinery manufacturer is the tendency towards municipal improvements, the result of winch is the construction of street railways, market houses, and electric light plants, as well as the introduction of improved drainage systems all over ths Republic. — Commercial Intelligence.

— Major B. Baden-Powell writes to The Times describing a visit he receiitly paid in Germany to the "dockyard,"' where an aerial steamship of vast size is in actual course of construction. "We have all read so much abovit such contrivances in the pages of Jules Verne and his hundreds of plagiarists that we are not too ready to believe in the realisation of such a dream. But liere we have the evidence of an eyewitness that the ship is actually on the stocks, and is to cost, when finished, about £70,000. It is made of aluminium, and has the appearance of an enormous bird-cage. Upon this framework an outer skin is to be stretched, and in the enclosed space a number of balloons are to furnish the rising power. The total lifting, capacity will be 10 tons, and in % gallery beneath will be the engines to propel the monster through the air at an estimated speed of 22 miles per hour. If there were no such thing as a wind, which bloweth where it listeth — and very often at a speed far greater than that stated — the aerial steamship might have more prospect of success than it seems to us to promise.

— The existence of a "green ray" or "green flash," at the moment the sun disappears from view beneath the horizon, is unknown to many but any careful observer can see the colour, especially when the sun sets in the ocean. The phenomenon has been often noticed by physicists, and has been thought by some to be an optical' illusion. The subject was recently discussed very fully in the French Physical Society. As reported in Science Abstracts, M. U-uebhard asserted that the green ray is "the grey shadow of the earth, feebly illuminated from the zenith and viewed by an eye fatigued for red ; it therefore appears green." M. Pellat stated his belief, on the contrary, that "the setting yellow sun has a red lower and a green upper border, sepal ately examinable in the telescope, and due to prismatic refraction by the atmosphere. The absorption which makes the sun's disc appear yellow makes the violet upper rim appear gi-eesi or greenish-blue- instead of violet. When the sun sets, the upper green rim can be seen for a fraction of a second, but can be kept longer in view if the observer go up a slope as the sun sets." M. Guebhard thought this was different from the green lay following the .setting of a red sun. M. Raveau said that he had seen "the sea coloured green in a triangle with its apex at the point where the sun set ; and the colour seems to flow away toward the horizon."

— Professor Lunge's recent address on the occasion of the first Hurter Memorial Lecture, before the Liverpool section of the Chemical Industry Society, was an extremely interesting one. Taking for his subject the impending changes in the general development of industry, and particularly in the alkali industries, he drew attention to some of the most recent discoveries and advances in connection with the big chemical processes. After an account of the progress being made, especially on the Continent, in the electric transmission of power derived from natural waterfalls, he pointed out that fossil fuel is hoar-ded-up wealth, to which nothing can be added, and which a little sooner or later will have ceased to exist, but water-power is a gift of topographical configuration, lasting practically for ever, and ceaselessly flowing through all centuries. The comparative advantages of those countries which possess the latter kind of wealth will consequently increase with the laps© of time. Taking a broad view of the question of fuel and of power, ami of the industrial development of mankind intimately connected with them. Professor Lungo distinguishes three great periods. The first extends from the dawn of history to a little more than 100 years ago, a period in which practically wood only was u°ed as fuel. The second division is our present coal neriod, the period which in one century has advanced the mechanical and chemical industries a hundred times more than all the centuries preceding it. From the rate at which the world's coal supply is now being used up, this period can only last a. few hundred years, and can thus only form relatively quite an inf ignificunt episode, leading \ip to the third period, when man will rely no more on those remnants of former epochs, but will carry on his work with the direct help of the solar energy incessautly pouring down upon the earth hx

the shape of heat, light, and other forms of radiation, partly transformed here into waterpower.