Science Siftings

New Zealand Tablet, 3 December 1908, Page 35

Science Siftings

BY * VOLT

Spilled Mercury^

Mercury spilled on table or floor is somewhat hard to collect, unless special precautions are taken, owing to its tendency to divide into small glotules, which roll away at the slightest touch. If a wet ring is made around the spilled mercury by the aid cf a wash bottle or other similar means, it will be found that the globules of mercury cannot cross the ring. The mercury can then be collected in a small shovel made from a piece of thin card or even an ordinary envelope.

The Cable Steamer Signal.

The ' telegraph * steamer is a vessel employed to lay down or pick up a telegraph cable, and every other boat, large or small, is obliged to keep out of her way. As a danger signal to other crafts the ' telegraph ' steamer displays two red balls with a white diamond between them, and if the vessel is moving through the water the red and green side " lights are also exhibited.

Weight of a Lion.

What does a lion weigh? Those who know the look of the king of beasts best and how small his little body really is will probably come farthest from the truth. About 300 to 350 pounds is a usual estimate, but a full grown lion will>tip- the scales at no less than 500 pounds. Five hundred and.: forty pounds is the record for an African lion. His bone is solid and heavy as ivory. The tiger runs the lion very close. A Bengal tiger killed by an English officer scaled 520 pounds. A tiger this size has, however, considerably more muscular strength than the biggest lion.

New Racing Device.

It is possible that in the near future the mono-rail gyroscope car, the invention of Mr. Louis Brennan, of torpedo fame, will become an important adjunct to racecourse equipment (says the Sydney Morning Herald). The inventor is brother to Mr. Joseph Brennan, official stenographer to the V.R.C., and the latter has written requesting him to construct a car with a seating capacity for half a dozen men, the vehicle to run on an elevated rail fixed on the outer edge of the racetrack, or inside the running rail, the vehicle to travel at the same speed as horses in a race. In this ' chariot of observation ' the stewards would be seated, and thus from start to finish of a race would have the movements of horses and riders under their immediate notice. Mr. Louis Brennan is now under contract with the Indian Government to instal a gyroscope and mono-rail outfit for a track of 100 miles in length, and when that is completed he may devote his attention to the ' chariot of observation ' suggested by his brother.

A Peculiarity of the Eyes.

It is a fact not generally perceived by the majority of persons that if we run our eyes along the side of a room, or along the horizon, the eyeballs do not follow the movement of the head with a smooth, unifocm motion, but keep in line by means of a series of quick, short, almost imperceptible jerks. At first one may not think that is so, but (says he New York Tribune) careful experiment "will prove that it is. If the eyes are fixed on a moving object, then the motion of the eyeballs in following the object is uniform ; but when it is the head that moves, while the objects looked at remain fixed, the eyeballs perform in the manner just described. It is not necessary in order to observe this phenomenon that visible objects should be before the eyes. Let the eyes be shut, the fingers pressed lightly on the closed Hds,\ and the head then turned from side to side. The little jerks . with which the eyeballs follow, the motion of the head will be distinctly perceived. Among the curious scientific experiments that have been made in the" effort to discover the meaning of this peculiarity of the eyes is one in which a turntable, large enough for a man to sit comfortably upon, plays a principal part. When the table is turned with a regular motion, the person sitting upon it, having closed his eyes, feels his eyeballs jerking 'as they follow the revolution of his head ; but as the table continues to turn the jerking gradually ceases, and at the same time the person imagines that the revolution is becoming slower, until at last, when the eyeballs no longer twitch, the table seems to him to have stopped turning. If, then, the table is suddenly made to turn faster, the jerking sensation is renewed; and if, on the contrary, it is made to turn more slowly, the same sensation is experienced. But now the person imagines that he is being revolved in a direction opposite to that of the actual motion.