Science Siftings

New Zealand Tablet, 19 May 1910, Page 795

Science Siftings

BY 'VOLT'

Electric Lamp Wires. On electric arc lamps it will be noticed that the wires which convey the current are nearly always twisted. This is not from any artistic point of view, but is purely for practical purposes. In the case of a break off at a terminal (that is the place where it meets the lamp), if the wire had been straight it would have necessitated the insertion of a new piece of wire or the making of a new joint; whereas, by untwisting a portion of the coiled wire, sufficient is available for the making of a new connection. These spirals also form a more flexible connection, and there is consequently less chance of the wire breaking when subjected to vibration. The Cork Oak. The cork oak grows -plentifully in Spain, and the peasants make use of the bark to light their houses at night. The bark is placed in a kettle, from which protrudes a spout; and when it is hot enough it give off a gas which burns with considerable brilliancy. If the family sit up late, several kettles of cork bark are used during an evening; but the lighting is not expensive, and the peasant is careful to save the carbonised cork refuse, for he can sell it, as it is known commercially as £ Spanish black,' one of the intensest black-browns known among pigments. Floating Islands. Of all passengers carried by ocean currents, floating islands are the most interesting. Many of them have been found voyaging on the Atlantic. These islands were originally parts of low-lying river banks which broke away under stress of storm of flood and floated out to sea. The Orinoco, the Amazon, the La Plata, and other tropical rivers often send forth such pieces of their shores. Some of the bits of land are of large size, and carry animals, insects, and vegetation, even at times including trees, the roots of which serve to hold the land intact, while their branches and leaves serve as sails for the wind. Generally the waves break up these islands shortly after they put to sea, but sometimes, under favorable conditions, they travel long distances. A Necessary Precaution. It is said that when the big guns on a battleship are fired, the crew plug their ears with cotton wool and meet the shock on tiptoe and with open mouths. If they did not plug their ears, open their mouths, and stand lightly on their toes the shock would have a disastrous effect. When the big _ guns roar and the quick-firers rattle, the great battleship trembles from keel to top, and this vibration raises a milky spume on the sea for many yards around. Volcanoes of water and foam rise near the targets where the half iron projectiles vanish. The height of the volcanoes is 173 feet. They linger "a long time in the air before collapsing thunderously. A seven-inch shell heaves up a waterspout 102 feet in height. The Legs of the Elephant. The legs of the elephant differ from those of more familiar large animals in the fact that the ankle and the wrist (the so-called knee of the horse's fore-leg) are not far above the sole of the hind foot and fore foot (resembling man's joints in that respect), whilst the true knee-joint (called the stifle in horses), instead of being, as in horses, high up, close against the body, strongly flexed even when, at rest, and obscured by the skin, is far below the body, free and obvious enough. In fact, the elephant keeps the thigh and the upper arm perpendicular and in line with the lower segment of the limb when he is standing, so that the legs are pillar-like. But he bends the joints amply when in quick movement. The hind legs seen in action resemble in the proportions of thigh, fore-leg, and foot, and the bending at the knee and ankle, very closely those of a man walking «on all fours.' The elephant as known in Europe more than three hundred years ago was rarely seen in free movement. He was kept chained up in his stall, resting on his. straight, pillar-like legs and their pad-like feet. And with that curious avidity for the marvellous which characterised serious writers in those days to the exclusion of any desire or attempt to ascertain the truth, it was coolly asserted and then commonly believed, that the elephant'could not bend his legs. Shakespeare—who, of course, is merely using a common belief of his time as a chance illustration of human character— Ulysses say (' Troilus and Cressida Act II.): ■ ' The elephant, hath joints, but none for courtesy; his legs are legs for necessity, not for flexure.'