Science Siftings

New Zealand Tablet, 8 November 1906, Page 35

Science Siftings

By 'Volt '

Improvements in Wireless Telegraphy. It is reported in. Berlin that those attending the Wireless Telegraphy, Conference are -greatly pleased with- - the success of Valdemar Poulsen's system of. wireless, telegraphy, which substitutes a continuous flow of energy for the old method- of transmission by intermittent sparks. Rendering Ivory Flexible. . - . Ivory may be tendered flexible by immersion in aj solution of pure phosphoric acid— specific gravity 1.13 — until it partially gains in transparency ; then it is washed in cold, soft water Itnd dried. It will harden - if exposed to air, but may again be "made pliable by immersing in hot water. Pampas'"Grass Hats. Half a million straw hats is no uncommon, sight to be met with at oiie time in the hat stores 'of Mexico. The hats "are made of a long pampas grass which grows nowhere else in the world. It is specially cultivated for the hat industry. So rapidly are the.hats made that some skilled workmen can turn out. , ten or a dozen a, day, and they are then sent t0., a1l - parts of the world. They cost about Id - each, to make, and are retailed at from Is 6d to 4s, and are so durable that it not unfrequently happens that those of an economical turn of mind make a single hat last ten years. - " . . The Elephant's Teeth. • Elephants have no front teeth, and they never eat fiesh or any food that requires tearing apart. Eight teeth are all they have, two above and below or* each side, huge yellow molars, as wide as a man's hand, and a couple of inches thick. Over these hay or fodder is shifted by the queerest, ugliest tongue in the whole animal kingdom, a tongue that is" literally hung on both ends, having no power of movement except in the middle, - where it shifts back ' .and forth from side to side, arching up against the roof of the big mouth like an immense wrinkled pink serpent. There is nothing stranger than the working pf an elephant's tongue, unless it be the working of 'his breathing apparatus when he sleeps. Elephants, like human beings, have two sets of teeth, the milk teeth, , which are smaller than the permanent, molars, fall out when about fourteen years old. These baby teeth," which are nevertheless . enormous, are occasionally picked up by circus men . among the fodder, and ' preserved as curiosities.. The Vision of Birds. Birds have very acute vision, perhaps Ihe" most acute of any creature, and the sense is also more widely diffused over the retina than is the case with man. Consequently a bird can see sideways as. ~wellas objects in front of it. A- bird sees, showing great uneasiness in consequence, a hawk long before it* is visible to man. So, too, fowls and pigeons find minute scraps of food, distinguishing them from what" appear to us exactly similar pieces of earth or gravel. Young chickens are also able to" find their own food, knowing its' position and how distant it is, as soonas they are hatched, "whereas a child only very gradually learns either to see or to understand the'distance of objects. Several birds, apparently the young of all those that nest on the ground, can see quite well directly they come out of the shell, but the'young. of. birds that nest .in trees or on rooks . are born blind and have to be fed. ' _" . . Color-blindness. - While glasses cannot fit the color-blind for observing signals at sea or on railways, Herr Pichon, of Cologne, finds that much assistance may be given in distinguishing between colors. Persons having* the" common form of color-blindness require red and grieen glasses, as the red glass absorbs' green rays . anff causes, red objects to appear lighter than to the » naked eye, and the green glass absorbs red rays and . adds to thebrightness of green objects." Those who are j ' colorblind to yellow and, blue can bo similarly helped by glasses' of yellow, or blue. In cases of color-blindness ' to all colors, three different, glasses — red, green and violet— are necessary, ....and these can be combined- in pairs so as to give twelve different shades,, making possible very accurate determinations. In a special kind of color-blindness, disease of the retina causes utter inability to distinguish blue, and an affection of the optic nerve makes it impossible to see red. '