Scientific and Useful.

Western Star, Issue 1116, 15 January 1887, Page 1 (Supplement)

Scientific and Useful.

SACCHARINE MOHTAE. Tho use of sugar, or saccharine liquor, for mixing lime and cements has been known in some parts of the world from “ time immemorial,” and many of those whose business it is to make plaster molds, or casts, mix the plaster of Paris with a solution of sugar in water. Surgeon-General W. R. Cornish calls attention to the fact that the practice of mixing jaggery or unrefined sugar, with mortar is very ancient, and masonry properly cemented with such mortar is not easily removed without blasting.—English Mechanic. THE RECENT ECLIPSE OF THE SUN. At Grenada, August 29, during the solar eclipse of that morning, good photometric observations was made by Professor Thorpe. The light during the middle of totality was less than from the full moon. Tho eclipse was well ohservi d by the British Astronomical Expedition, and in the observations taken it was noticed that the corona extended nearly two diameters from the sun, and exhibited a feathery structure at the poles. Good photographs have been obtained of the coronal spectrum in the blue end. The spectrum was similar to that of the eclipse of 1883 observed on the Caroline Islands. BOILER EXPLOSIONS IN GERMANY, Last year there were 13 boiler explosions in Germany, against 14 in 1884 and 1883, and 11 in 1882 and 1881. The number of casualties to persons was 22(against45 in 1884 and 55 in 1883), the number of fatalities being 11 (against 12 and 23), while two persons were badly injured and 9 slightly injured. Of the boilers which exploded, 3 were vertical, 8 horizontal, and 2 tubular, according to Kuhlow, a Berlin contemporary. The cause of explosion was in three cases local weakening of plates, in three cases want of water, in two cases defective construction, and in one case each accumulation of firs, high pressure, faulty action of tubes, weak and defective construction, and careless attention. During recent years there has been a notable falling off in the number of explosions as in that of fatalities. STEEL FOE BOILER-PLATES.

r Jhe Committee of Lloyd’s Registry for British and Foreign Shipping, haring been advised by their technical engineering staff that it was fitting that there should be greater stringency as to the tests to which steel for boilers is subjected, have issued modified instructions ou the subject. Formerly all steel for boiler-plates was required to have an ultimate strength of not less than 26 or not more than 30 tons per square inch of section, with an ultimate elongation of not less than 20 per cent, in a length of eight inches. In the matter of elongation their requirements remain the same ; but, as regards the breaking strain, a sliding scale is adopted as follows : The material of stays and of plates, not exceeding 1 inch, in thickness, is to have an ultimate tensile strength of not less than 26 and not more than 30 tons per square inch of section. In plates above 1 inch, and more than If inches in thickness, the ultimate strength must not be less than 26 and not more than 29 tons per square inch, and in plates above If inches in thickness, not less than 20 and not more than 28 tons per square inch. Previously the temper test was only applied to samples taken from every plate intended to be used in the furnaces and combustion chambers, but in future it is to be applied to samples taken from overy plate used in the construction of boilers. It may be expected that this increased stringency may produce better results in steel, but would it not be advisable to limit the breadth and area of steel boiler-plates ? 8o far as we can gather from a careful consideration of this important matter, there is a great danger iu large steel plates being unreliable, through irregularity in cooling causing local defecis. For iron and steel vessels, Lloyd’s Register apparently views with suspicion the use of very broad shell-plates, and sometime ago practically prohibited the use of plates over 4ft. 6in. in width. Is there not much greater reason to object to wide boilerplates ? WOODITE.

A new substance, to which the name of “Woodite” has been given by Sir E. J. Eeed, M.P., after the name of the inventor Mrs A, M. Wood, was exhibited to a number of gentleman lately at 11 Delabay Street, Westminster. The material is an indiambber composition, specially prepared, It is noninflammable, and practically impervious to the action of salt water, while the atmosphere does not appreciably affect it. It is highly elastic, and made in blocks varying in size of the projectiles it is intended to be used against. The material was submitted to Sir E. J. Eeed for experiment, who has reported favourably upon it. The applications of the material are divided into two classes—viz,, plans for defending vessels against the attacks of guns, rams, torpedoes, &c., and certain other plans for use in case of accidental collisions. It appears that light projectiles driven through it only rend the material, which returns again to its original position, closing up the hole, and remaining perfectly watertight. Some days ago a number of experiments were made upon a 4ft. target at the Nordenfeldt range at Hartford, with satisfactory results. Three and 6-pounder quick-firing Nordenfeldt guns were used and iu every instance the projectile passed through the woodite and punched a hole in the iron backing two or three inches in diameter. The only effect on the woodite observable was a slight mark to indicate the poiut of entry. So completely had it closed up again that no water could possibly pass through. In the opinion of experts present the material was likely to prove ot great value in promoting the satety of vessels subjected to the lire of artillery. Various other applications of the material were shown among wuich we may mention a model of a double reversible lifeboat, a model of a single lifeboat, also for boats’ fenders and the protection of piers and wharves. CONSTKUCTIOK OP A KEW PIEB IN CX.EAVEliAND. The Skinningrovo Iron Company are about to put down a solid cement pier, similar to that constructed by the Tees Conservancy Commissioners at the mouth of the Tees. Tha Pier will be extended 150 yards beyond the end of their present tip, and the harbour will be formed by the blasting of the rock, in order to let the vessels lie in all conditions of the tide. To protect the harbour the pier will be extended in a southerly direction after getting out the desired length, and, if necessary a second pier will be made a little to the south, and thus give an entirely closed harbour. When the work is completed the advantage accruing to the district will be great—markets hitherto inaccessible will be opened and easily reached by sea from the whole of the eastern portion of Cleveland. Nor will the harbour be used alone for ex porting pig iron—a portion of the fuel required to carry on the works may be brought by sea instead of by land, and eventually it may become a fishing port, there being direct communication from the pier to the North-Eastern Railway. The undertaking is an important one, and the efforts of Mr Hutchinson (the managing director of the company) must beneficaliy affect the whole district.