SCIENCE SIFTINGS.

Auckland Star, Volume XXXIX, Issue 76, 28 March 1908, Page 12

SCIENCE SIFTINGS.

BIRDS MIGRATE IN SEARCH OF LIGHT. Professor Schafer believes that daylight alone determines bird migration. The summer migrants, he tells us, come north to take advantage of the longer days, and go south again to avoid the short and dark ones. They require all their time to get sufficient food for themselves and their voracious young, and hence the extra daylight of the north in summer is an advantage to them. In winter the short days do not allow them time to get sufficient. Most birds require daylight for feeding. Professor Schafer does not credit the old explanation that migration is due to cold and want of food. species leave this country while it is. still warm, and food still abundant. WORMS AS TREE PLANTERS. It has long been a matter of common knowledge that squirrels aid the forester by burying nuts, of which some sprout and ultimately develop into trees; but that he is also indebted to earthworms for aid of a similar nature is claimed by Mr. E. A. Andrews in the "American Naturalist" to be a new discovery. In America it appears that the dry, flat fruits of the silver-maple are frequently employed by worms to plug the apertures of their burrows, in the fashion long since described by Darwin. In districts too dry for them to germinate under ordinary conditions, a certain proportion of maple-seeds thus drawn into their holes by the worms were found to sprout and grow into seedlings; and although these ultimately perished under the influence of the late summer drought, the author is of opinion that under less unfavourable conditions a certain number would survive. Worms, he concludes, "probably more than amend, by planting trees, tbe damage with which tbey arc credited through destroying seedlings in gardens." NATURAL AND ARTIFICIAL GEMS. The laboratory of Nature is still more efficient than the electric furnace in the making of gems. The artificial sapphires and rubies made in Paris have the composition of tne natural stones except in the small amount of material added for colouring, but their difference seems to be considerable. The artificial sapphires are softer than the real, lighter in weight, and they refract the light much less brilliantly. As a source of blue colouring, chrome was tried unsuccessfully, and the process actually employed is a secret of the sapphire-makers. The red of the artificial rubies is given by cobalt. ENGRAVING BY TELEGRAPH. In the production of engraved plates by telegraph, Carbonelle, a Belgian, uses a picture prepared with thick non-con-ducting ink, and this is wound upon a revolving cylinder under a stylus in electrical connection with the telegraph line. The receiving cylinder is covered with some soft metal like lead, over which is a stylus that gives a cut varying in depth with the intensity of the current from the stylus. The resulting plate is ready for the printing press without change. BIG ELEPHANT TUSKS. The largest known. tusE" is" one from East Africa in the possession of Sir E. J. Loder, which measures 10ft 4in long, with a girth of 26in, and weighs 2351b. The longest tusks are a pair from East Africa recently in the possession of Rowland Ward. Their respective lengths were lift oiin and lift, and their united weight 2931b. THE MACHINE-GUN SILENCER. A remarkable apparatus has been invented by an Indian official which seems likely to revolutionise machine gun lire, says the " Standard." The object of the , invention is to silence the tell-tale noise of the machine gun, thus rendering its value in the .field far greater than that of companies of infantry. The inventor is Mr. Alfred Thompson, who is serving on the . Indian Establishment as Chief Examiner of Machine Guns. The discovery : has been known to the military authorities for some time, and although Mr. Thompson has been working for years at the process he has only recently brought it to a state of perfection warranting extensive trials. The 'silencer" is an apparatus which is attachable to a gun the inventor having given al his time to making it adaptable to. the Maxim The insistent crack of the Maxim is reduced by the invention to a slight detonation wmeb-.s indistinguishable beyond a range of 000 yards. ° THE GREAT CATARACT. In'the course of a lecture delivered by Professor G. Frederick Wright, it was stated that at the beginning of the Christian era the edge of the Horseshoe cataract at Niagara was 1J miles lower down than now, and at the time of the Trojan War it was at the head of the whirlpool rapids, nearly three miles below. At the period of human history marked by recent discoveries in Egypt and Babylonia, this marvellous cataract was just beginning its work of erosion, while Canada was as well within the grasp of the glacial epoch as Greenland is to-day. OYSTERS AND THE X-RAYS. Some years ago Professor Raphael Dubois, of the University of Lyons, conceived the idea of examining pearl-oysters by means of the X-rays. Experiments proved that, in spite of the natural thickness of the oyster's shell, the presence of a ! pearl, no matter how small, could always be detected. This method has been employed by a Mr. Salamon, an electrical engineer of New York, who states that the results have been in every respect At the cost of £S,OOO, Mr. Salamon has constructed an apparatus which enables 24,000 oysters to be examined in an hour. A TALL. TOAD STORY. An American paper says: —Director Hornaday, of the New York Zoological Park, has placed upon exhibition a toad which he believes to be not less than 1,000 years old, it having been found several months ago in a pocket of a block of limestone in a silver mine at Butte, Mont., 500 feet below the surface of the mountain. When found the toad appeared to be dead, but upon instruction from the operator, who knew Mr. Hornaday, it was placed in a glass jar, sealed up, arid sent to New York. There an inspection revealed the truth that it moved sluggishly, although the eyes had long been useless and it had neither eat-, en nor drunk for centuries. This appears to prove tbe old theory that toads can live untold years in a state of suspended animation. The director believes that if he should try to feed the creature it would certainly die. It is quite plump and a perfectly-formed, medium-sized toad of I -the spadeiaot variety.