Notes on Science, Mechanical Inventions, Etc.

Oamaru Mail, Volume XXI, Issue 6763, 10 December 1896, Page 4

Notes on Science, Mechanical Inventions, Etc.

SELECTING BEICKS. - ~ In selecting bricks it should be ascertained that they are hard and well-burnt throughout, and free from cracks, flaws, or stones; they should be free from lumps of lime, as this substance will often cause them to split after being walled, although they may have been wetted before using. They should also be uniform in size and color, and should not absorb more water than one-sixth of their weight. Many pressed bricks are almost completely non-absorbent, and are practically impervious to water. Bricks should also be selected of sufficient strength to resist any stress to which they may be subjected. WHAT IS A CANTILEVER ? A cantilever is any projection supporting a load, or, in its geometrical form, it is a semi-beam fixed at one end and free at the other. To speak with mathematical precision, hat and coat pegs, shelf brackets, cart shafts, barrow handles, and many other common objects are cantilevers, and their strength would be estimated in the same way as if they were cantilever girders. The term is usually applied to the projecting supports, under a balcony, the brackets carrying the footway of a swing bridge, etc. The Forth Bridge is called a cantilever bridge because it practically consists of semi-beams projecting from the piers, and carrying a connecting piece at their ends to form the continuous bridge. A HINT FOR USERS. OF INCANDESCENT GAS BURNERS. To those who use incandescent gas lights in towns where they have no gas on during the daytime, and therefore cannot use by-pass burners to any great advantage as regards the life of the mantle, it may be interesting to know that they can light the burners from underneath the chimney without causing a shock to the mantle, by placing the taper or spirit lighter inside chimney near bottom of mantle and then turning on the_ gas gently. By this means the gas is lib at once, before it accumulates inside the mantle, as it does in cases where they are lit from the top of the chimney, as may be known by the report which they make when lit, this being a miniature explosion which destroys the mantle. ARTIFICIAL STONE. Artificial stone for paving-slabs, steps, window and door heads and sills, and other dressings suitable alike for cottages, or villas, can be easily and cheaply manufactured if a proper system is adopted and suitable moulds and ingredients are used. For strength and durability such artificial stone will compare with some natural stones on the market; in fact, places could be mentioned where the artificial stone, with ornamental and elaborate mouldings and finish, is outliving the natural stone, and while the latter is gradually decaying, the former, instead of showing signs of decay is actually hardening. Artificial stone can ba economically manufactured only when suitable materials are to be obtained in the locality, for the cost of carriage of material added to working expenses would leave little or no margin for profit, Crushed bricks, small gravel, cinders from furnaces, broken clinkers, coke breeze, ballast, and sharp sand can all be utilised, and there are very few places were some of the above can not be obtained. In grafnite districts granite chippings and dust are largely employed. MONEYED EXPEDITIONS. Mr George Gould, the American millionaire, who has just reiurned to New York from a trip to the Arctic regions, and is going to try and reach the North Pole by a series of relay journeys, says that a scheme of this kind has been prevented heretofore by the want of money. Here is what Captain Mayne Reid thought of moneyed expeditions : " Many a vast and pompous expedition has gone forth regardless either of expense or waste—aye, many a one that has returned without having accomplished the object intended. ' Too many cooks spoil the dinner' is a familiar old adage, very applicable to exploring expeditions, and it is a question whether unaided individual enterprise has not effected more in the way of scientific and geographical discovery than has been done by the more noisy demonstrations of Governments. At all events, it is certain enough that the exploring expeditions to which we are most indebted for our geognostic knowledge are those that have been fitted out with the greatesb economy. As an example, I may point to the tracing of the northern coasts of America, which, after costing enormous sums of money and the lives of many brave men, has been done, after all, by the Hudson's Bay Company with a single boat's crew, and ab an expense that would nob have frankled one of our grand Arctic exploring expeditions for a week." THE MANGO TRICK. The Indian " mango " trick, in which a plant is seen to grow up from .the seed in a few minutes, has been done in a new way by M. Michael Corday, of the Ecole Polytechnique, in France. M. Corday employs the well-known cinematograph, or apparatus for producing "living photographs," that is to say, photographic images endowed with movement and apparently with life. A rose plant is photographed at intervals during its growth until the flower buds and blooms. The photographs thus taken are combined by the cinematograph and projected on a screen, so as to represenb the development of the plant in a short time. The number of photographs taken in six months 'should be equal to the number which the sensitive band of the cinematograph will contain. Obviously the same plan will be able to show the changing aspects of the country during the seasons in one progressive illusion, and'it is suggested that it might be employed with advantage in illustrating various scientific experiments and natural processes of an evolutionary or gradual sort. ALUMINIUM RAILWAY CARRIAGES. On the French State railways it is stated that a number of passenger cars in which all the parts were formerly manufactured from brass* copper, and iron, with the exception of axles, wheels, bearings, and springs, brake, beams and couplings, are to be constructed with aluminium. The weight of a car provided with aluminium fittings is lj tons less than that of the old coaches. As an ordinary train in France consists of 20 vehicles, the weight of the train would be reduced by 30 tons. DRAINING THE ZUYDER ZEE. The special commission appointed by the Dutch Government to discuss the scheme of draining the Zuyder Zee has recently submitted its report, which states that such an undertaking is-quite possible. The work would take 31 years for completion, and every year 10,000 bactares (about 40 square miles) of land would be restored to cultivation. A dyke 30 miles in length will have to be constructed, extending from the extreme end of North Holland to the western coast of Frieslahd. The building of this dyke, which will be of a width of 35 metres (about- 115 ft) at the base and 6 metres (19ft) high, will take nine years. PSYCHOLOGY IN THE TREATMENT. OF DISEASES. There are symptoms (says the Pall Mall Gazette) that psychology will in time play a leading part in the treatment of morbid humanity, though for many years:there, hasexisted a professional repugnance to its methods. The facts of mesmerism and hypnotism have gradually overcome professional repugnance, however,; and are now pretty widely ■- recognised. Many members of the-medical profession; are nob above employing the assistance of : hypnotic agents -in the treatmenfcof nervous disorders, and some even-pracbise the suggestion themselves. -There- is.,a

well-known qualified lady doctor who has in this way successfully treated cases of confirmed inebriety; and who uses it also, for confinements if requested to do so.