Science Siftings

New Zealand Tablet, 24 June 1915, Page 47

Science Siftings

By ‘Volt.’

Persian Carpets. Aniline dyes have not added ,to the reputation of the carpets of Persia. At one time the only dyes used in the Persian carpet industry came from indigo, madder, and vine leaves. From these were evolved many delicate shades impervious to the action of sunlight. With aniline dyes the colors fade much more rapidly. In Persia you may see new rugs spread on the floors of bazaars, so that many feet may tread on them. By such hard wear —provided the colors are fast—the genuine article improves in appearance, acquiring an attractive gloss. A Persian carpet of the best kind has a marvellous number of stitches, and a hearthrug of pure silk may cost hundreds of pounds.

Timing Trains.

A railway official explained how a train’s speed can be told, with accuracy while travelling. He pulled out his watch, and, after quickly glancing at it, peered intently out of the window. In a little while he remarked quietly: ‘ This train is going between 31 and 32 miles an hour. If you are ever curious about it, just look ,at the inside of the outer rail on the opposite side of the line for a minute or two, until you find that you can distinguish where one rail joins the other ; then count the joints, and as many rails as you pass in 21 seconds is the number of miles your train is travelling an hour.’

Facts About Rifles.

No two of the European armies now engaged in war are equipped with the same rifle. The French and Austrian forces are using the largest calibre instruments found on the Continent, while the latter, at the sacrifice of velocity, is employing the heaviest bullet. The German rifle attains the greatest muzzle velocity, but this is partly on account of the fact that it uses the lightest projecile shot by any small arm in Europe. The longest rifle in service belongs to the Russian equipment, while the French have the longest, bayonet, a thing which gives their weapon the greatest total length, and therefore an advantage in charging. The shortest gun is that of the British Army, and with the bayonet added the instrument is still shorter than those of any countries except Belgium and Austria. Owing to the small size of the gun, however, it may be handled with ease.

Monster Fog-Horns

One of the new monster fog-horns in the United States lighthouse service is capable of emitting a sound that can be heard 25 or 30 miles at sea. It looks like half of a submarine boat, and a man of ordinary stature can easily step into it. The horns rival the great brazen ceremonial trumpets of the Uriankhais, in Mongolia, ■which, 10 feet in length —and probably the largest of natural wind instruments—are supposed to carry to the farthest reaches of the heavens. The mechanical foghorn makes a doleful sound, and in this it is the big brother, of the great Mongolian instrument, both of which are intended to bring the good and ward off the evil event. The new fog-horns are worked by compressed air furnished by an engine of from 20 to 25 horsepower.' Distance Soldiers Can See. ' Some interesting experiments have been made with the object of discovering at what distance the recognition of one soldier by another is reliable. Dor soldiers with good eyes. it was found that a person seen once before could be recognised at a distance of 80 feet, while an acquaintance could be recognised at a distance of 300 feet, and an intimate friend or relative at a distance of 500 feet. The various parts of a man’s body can be distinguished and any decided movement can be detected by an expert rifleman at a distance of 300 feet. At 1800 feet a man appears as a spot on the landscape, and cannot usually be.seen if he keeps still or if his dress does not contrast with the background. V 4:"