Science Sittings

New Zealand Tablet, 29 June 1911, Page 1219

Science Sittings

BY ‘VOLT’

The Ventilation of Tunnels. Falling water finds a new application in the ventilation of tunnels and other underground structures; - Passing, through a sieve it is made to fall in a fine spray through a - pipe whose lower end is below the surface of the water of an underground tank. This spray carries air with it 'which it forces through the water and up into an air-chamber in the upper portion of the tank. From this it is fed into the -tunnels under the constant pressure caused by the fall of the water. ' : A Remarkable Alloy. “ A remarkable alloy ; Ruebel bronze, has been prepared in Germany. Magnesium, its main constituent,:is mixed with zinc, copper, and aluminum. Like the other recent alloys, it joins high tensile strength to low specific gravity. It promises to be most useful in the construction, of airships, as it will reduce their weight to one-third or onefourth of what it is at present. -’5 AKv’ -• ; Faced with Metallic Coatings. Cloth, paper, wood, and metal are now effectually faced with metallic coatings by a spraying process. The fused metal is discharged through a fine < orifice and converted into a fine spray by a. current of air or gas forced across the jet at a high pressure and at an angle of 90 degrees. The minute particles deposited are then cooled by an air or gas jet to prevent ignition of the coated material. Improving the Efficiency of Blast Furnaces. Though seemingly paradoxical, the fact is fully established that the efficiency of the blast furnace is greatly increased with the refrigerating of the air before injection, The refrigeration causes the air to become dried' before coming in contact with the flame, thus economising the heat of the. furnace. The process'is said .to effect a net saving of from 30 to 35 per cent, in fuel. r Copper-clad Steel. Copper-clad steel of ,any desired thickness in which the two metals are so intimately united that the combination may be submitted ,to any of the usual processes of working metals, has been* manufactured recently. The qualities of this new product are worthy of note. The tensile strength is equal to, and sometimes greater than that of steel of the same sectional area. It answers well as a wire tor electrical and mechanical purposes, and for the same ohmic resistance, a much smaller size is required than when •galvanised iron wire is used. The resistance of the coni--bined metal is about the same as that of copper. , Minerals in the Philippines. -The annual report of the Bureau of Science, Department of the Interior, Manila, on the mineral resources of estimates the output of gold for 1909 at imo dollars, an increase of 14 per cent, over the year 1908. Ihe production of coal was 30,336 tons, a 155 per cent, gam over the previous year. This yield comes from *' vG mines on the island of Batan, one at the extreme east and the other at the extreme west of the island. The coal appears .to be of the Tertiary age, and is classified as subbitummous, is low in ash and satisfactory for steam production. 1 The Isthmus of Panama, -. The railway across the Isthmus of Tehuantepec from the Atlantic to the Pacific was opened in 1907, and in that year merchandise to the value of 10 million dollars passed between American ports by that route, the value of east bound _ and; of west-bound-freight being about equal. At that time the steamers of the American Hawaiian Co. were making through voyages from New York to the Pacific Coast and the Hawaiian Islands via the Straits of Magellan carrying general cargoes on the outward voyage and Hawaiian sugar. chiefly ion the home voyage. The company determined" in 1909 to use the railway and divided its fleet into two parts, one to trade between New York and Puerto Mexico, the ■; Atlantic terminus of the road, and the other between Salina Cruz, the Pacific terminus, and. the Hawailan Islands rand, ports on the .American Pacific seaboard. This - caused; American trade by the Tehuantepec railway to increase greatly. ~; For 1910 it amounted to 70 million dolla..s > nearly ; 42 millions being west bound goods and 28 millions being east bound. Of the former, 32 million dollars went to. California, four and a-half millions to Puget Sound and three and a-half. millions to Hawaii. Of the latter million dollars worth was from Hawaii, six millions from California, and the remainder; from Puget Sound. Thus California merchants are beginning to use the Tehuantepec route as a competitor of the railways. Nevertheless, the latter hardly feel -the competition; so great has -been the development of the whole Pacific Coast during the past ten years. This development tends to increase rather than to remain constant ; hence, when the Panama Canal 'a finished, there will be enough trade . with the Pacific for both the railways and for the canal,