Science Siftings

New Zealand Tablet, 12 February 1914, Page 53

Science Siftings

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Preventing Motors from Back-firing. One of the most formidable and greatly dreaded causes of accidents in flying-machines is back-fire in the carbureter. As the result of an. attempt to solve this serious problem an ingenious device has been invented. The instrument does not pretend to prevent back-fire, but is intended to prevent 'damage by putting out the fir© before it can reach the gasoline tank and other parts of the machine. A two-way cock on the carbureter is connected with a lever normally held down by a fusible plug which melts at a temperature of 140 deg. Fain . A plug fusible at any desired temperature may also be used. When a back-fire occurs the plug is melted, and this allows a small steel soring to act upon the lever, closing the fuel line to the supply tank. It also opens, simultaneously, a vent which allows the fuel remaining in the carbureter to be drained to a point below the fuselage or to any point outside the danger zone. The Value of Telegraphy. A very curious example is given as to how the telegraph has reduced the size of the earth. Not long ago, a woman on Valentia Island, County Kerry, was taken suddenly ill. The Island is peopled mainly by the operators and engineers who look after the cables laid between that point and Newfoundland. The nearest doctor lived at another cable colony at Waterville, on the mainland. Strange to say, there is no means of communication between Valentia Island and Waterville, which are about ten miles apart. But the cable operators at Valentia were not to be beaten. They asked their Newfoundland colleagues if they could communicate with their end of the Waterville cables, and the reply was that the two Newfoundland offices were connected by telephone. Thereupon the Valentia men sent a message to Waterville via Newfoundland asking the doctor to attend the sick woman. The doctor arrived in two hours, and landed amid cheers from the little colony of operators. The History of Zinc. Zinc was introduced into Europe in the seventeenth or eighteenth century by men from India. It was known then as calaem, splauter, or tuttanego, and was the same metal which the famous alchemist, Andreas Lebavius, described in 1606, and which he declared consisted of silver, cadmia, mercury, and arsenic. Late in the sixteenth century keen competition was, going on between the Portuguese and the Dutch in the Indian seas, and, a Portuguese ship having been captured by the Dutch, her cargo of calaem or ‘ Indian tin ’’ found its way into Europe. Nobody at that time knew what it was, and it was a piece of this cargo that became the subject of analysis by Lebavius. Zinc, it seems, was first produced in India, but soon became an important industry in China. China was the sole producer of zinc until the middle of the eighteenth century, disregarding a minute quantity of that metal which was occasionally obtained as a by-product in the lead furnaces of Goslar, in the Harz Mountains. All About Corks. Very few people understand how corks are made, or where cork trees grow. The cork tree, on an average, lives 100 years, and its average height is 25 to 30 feet. It is a native of the Mediterranean basin in northern Africa, Corsica,, southern France, and the Iberian Peninsula. It does not grow in America except in spots dry, -warm places 'of mild temperature. These trees are very rare, and considered great curiosties. The cork tree is valued for its.bark; the best time to strip it is in July or August. The outer bark of the tree is first stripped when it is about 25 years old. ‘ This removal of the rough bark, or outer skin, as some would call it, causes a growth of finer quality. This requires about eight or nine years, and the quality improves with ,each successive stripping. / • s ,