SCIENTIFIC.

Otago Witness, Issue 1901, 10 July 1890, Page 41

SCIENTIFIC.

— A French journal gives some particulars of the oscillation of a chimney stack near Marseilles, 115 ft high, with an exterior diameter at the top of 4ft. During a severe storm it was determined, by observing the shadow of the chimney, that its greatest oscillation was nearly lft Bin. It was further observed that a chimney set in motion by a gust of wind oscillates from four to five times backward and forward until it is at rest again. M. E. Burg asserts that should this momentum, during the oscillations of a chimney, repeat itself in such a manner that its direction coincides with that of oscillation, the overthrow of the chimney may be expected. This is the explanation given for the destruction of many a chimney constructed in accordance with sound principles of stability. In the case of a chimney near Viennn, 164 ft high, and constructed of concentric hollow iings, with an inner diameter to the top of 6£ft, which is exposed to considerable gusts of wind, the oscillations were most carefully and repeatedly measured with a theodolite, when the observations showed an extreme oscillation of only Hi centimeters (16£ in) during severe storms. — In the matter of recent inventions perhaps the most valuable is that adopted by the French Government for testing the strength of steel for guns. By this contrivance the breaking stress is indicated by the height to which mercury is forced up a vertical glass tube. The specimen to be tested is clamped between two shackles, odo of which is fixed, and the other attached to a piston rod of a hydraulic cylinder. A small pipe communicates the pressure on the face of a piston to a second and very much 3maller piston. This forces down a diaphragm, closing a larger cylinder, which is filled with mercury. As the mercury rises in the tube, an attendant marks the result, noting the point at which the mercury falls, which corresponds to the moment when the specimen breaks. The limit to the elasticity is thus ascertained, and the stress in tons per square inch is at once known. —In an article in the Baltimore Sun Professor Blumfield, of John Hopkins University, discusses the question of the number of races, and shows that whatever the number, colour is accounted the most distinctive characteristic of the race. The colour of the negro has been attributed to the deficiency of oxjgen in the warm air he has breathed. Owing to a weaker respiration, produced by deficiency of oxygen, a deposit of carbon is made in the skin. The carbonaceous matter in the blood is not sufficiently consumed, and so the tissues are laden with it as a chimney with a defective draught is choked with soot. — A new mineral oil, which will be known as "dynamine," having the consistency of nutter, has recently been introduced to tho manufacturing public by La Compagnie Francaise dcs Graisses Minerales Consistantes. The new substance is not acid, and is free from resinous matter and drying oils. It is very stable in character, and does not undergo any change when exposed to the air. Its buttery consistency does not appear to be due to the addition of paraffin, vaseline, or wax to a liquid oil, as it has a definite melting point at 84deg 0., and does not inflame at a temoerature lower than 220deg. In colour it resembles butter, and it has no appreciable odour. These properties give it an especial value as a lubricator, and as it has no chemical action on metals, dynamine is likely to be extensively used for this purpose. — The liver, whose functions i 3 to secrete from the blood the carbon not carried out in the form of carbonic acid in the act of respiration, is retained in the tropics, frequently, it is said, to the point of disease. The place of origin of the negro and the dark races of India and New Guinea is said to have bsen Lemuria, a continent supposed to have existed in a former geological period in the Indian Ocean. This continent, stretching east and west, is supposed to have embraced New Guinea, the Malayo-Polynesian Archipelago, Ceylon, Madagascar, and part of Africa The dark colour common to the people of all these regions is supposed to have originated in Lemuria anterior to the period of submergence of its more low-lying parts. —There grows not a seaweed nor a particle of vegetation in the eastern part of the North Sea. Such is the information, based upon recent researches, which Major Reinhold has been giving to the Kiel Natural History Society. The reason given is that the strong tidal currents prevent the germs and spores of marine plants from settling on the sea bottom. Where there is no sunlight no plant can grow, but this cannot be the reason for the vegetable barrenness in question. The very deepest part of the German Ocean is less than 400 ft. Now, the rays of the sun are believed to penetrate to a depth of 1200 ft, beyond which there is everlasting darkness — except the phosphorescent lights produced by the animals down there.

— There seems to be really nothing that electricity cannot do. It is now practically possible to see through iron or steel inf ots and discover any flaws or bubbles in their interior. We do not see these flaws in the popular sense, but a curious little electrical instrument called the " Schiseophone " will indicate the exact spot in which they are' located, which ib just as good. —It is said that one Dr George Tenius, of Vienna, has a process for the manufacture of artificial leather from red beeohwocd. The best wood for the purpose is taken from 50 to 60-year-old trees, cut in the spring, which must be worked up immediately, bark peeled off, steamed, treated with chemicals in a kettle under pressure, and exposed to several more operations which the inventor does not mention, as he wants to have them patented. From the prepared wood, strong and thin pieces are made by means of pressure. The inventor states that solid sole-leather can be obtained, which he claims is superior to the animal leather in firmness and durability, and can be worked up in the same way as animal leather, nailed and sewed.

— Many railway engineers havo remained sceptical as to the advantages of applying the compoundprincipletolocomotive engines, although in the ca«e of stationary engines these advantages are now freely conceded, but the experiments of Mr Urquharb, a wpllknown locomotive engineer, put the mat tpr beyond doubt, as he has run simple and compound locomotives side by side at the same

work, and found the compound engines to manage it on 20 per cent, less fuel.

— Even Dreamland seems to have secrets for the scientific explorer. An examination of some 4000 of his own dreams has given Dr Julius Nelson, of New York, some interesting results. It was found that the dreams of evening: usually follow great fatigue, physical or mental, and are associated with the events of the day. This is also true of night dreams, which, however, have more of a terrifying element. The pleasantest and most remarkable dreams are those of the morning, when, the brain being rested, fancy works freely and actively. The vividness of Dr Nelson's dreams fluctuated regularly in periods of 28 days, and also varied with the seasons, so that the "dreams of December were very vivid, and those of March and April least distinct.