SCIENTIFIC AND USEFUL.

New Zealand Graphic, Volume XIV, Issue VII, 16 February 1895, Page 152

SCIENTIFIC AND USEFUL.

KILLING GRASS BY ELECTRICITY. It is said that an American Railway Company has in successful operation a device for killing out the vegetation from its tracks by the use of electricity. It has always been a problem bow to keep down grass and weeds that grow along lines of railroads, and its extermination costs annually a large sum of money. The railroads have always been on the lookout for a device that would do the work effectcally and cheaply, and it looks as though this had been at last found. An electric generator, with a small engine to operate it is mounted on a flat car. The generator is connected with a brush made of fine copper wire, which reaches clear across the track to the ends of the ties, and comes within an inch or so of the ground. The car is pushed over the track to be cleared at the rate of about five miles an hour, and the electric current passing through the brush kills every weed and blade of grass that it touches.

WOMAN’S HEIGHT AND WEIGHT. A woman of five feet should weigh 110 pounds. A woman of five feet one inch should weigh 115 pounds. A woman of five feet two inches should weigh 120 pounds. A woman of five feet three inches should weigh 127 pounds. A woman ot five feet four inches should weigh 134 pounds. A woman of five feet five inches should weigh 142 pounds. A woman of five feet six inches should weigh 146 pounds. A woman of five feet seven inches should weigh 152 pounds. A women of five feet eight inches should weigh 160 pounds.

MAKING HAIRPINS. For years the English and French controlled the manufacture of hairpins, and it is only within the last twenty years that the goods have been produced in America to any extent. The machinery used is of a delicate and intricate character, as the prices at which the pins are sold necessitate the cheapest and most rapid progress, which can only be procured by automatic machinery. The wire is made expressly for the purpose, and put up in large coils, which are placed in a clamp, which carries it to the machine while straightening it. From there it runs into another machine, which cuts, bends, and by a delicate and instantaneous process sharpens the points. Running at full speed these machines will turn out 120 hairpins every minute. To economise it is necessary to keep them running day and night. The difficult part of the work is in the enamelling, which is done by dipping the pins in a preparation and baking in an oven. Here is where the most careful and constant attention is required, as the pins must be perfectly smooth and the enamel have a perfect polish. The slightest particle of dust causes imperfections and roughness, which is objectionable.

THE POWER OF ALUMINIUM. The power of aluminium to resist the corrosive action of water is one of its most valuable features. Experiments recently made with it in this connection at the Physical Institute of Berlin, were, it is reported, attended with the following results : —A tube of aluminium was taken, found on analysis to contain -58 per cent, of silicon and 32 per cent of iron, without a trace of lead or copper, also an aluminium plate containing *72 per cent, of silicon, -50 per cent, of iron, and -25 per cent, of copper. The experiments showed that aluminium, after immersion for 120 hours in water of varied composition, was corroded, this corrosion being strongest with hot water obtained from the town supply and least with cold distilled water. The corrosion extended uniformly with the interior of the metal. But although these trials show that the use of aluminium, from a chemical point of view, should only be resorted to under exceptional circumstances, they do not detract from its proved merits under ordinary conditions. 1

DOUBLE STEAM HAMMERS. These are entirely independent of each other in their working ; one can strike quick light blows whilst the other is striking slowly and heavily, or one can work alone whilst the other remains at rest. They are evidently constructed with a view to economy, the baseplate, anvil block, and central standard being common to both hammers, ’it is often convenient to prepare a forging under one hammer and pass it on rapidly at the same heat to the dies in which it is to be finished, and in such cases, it is claimed these tools offer decided advantages, since the plain pallets or preparatory dies can be fixed in one hammer and the finishing dies in the other, thus avoiding all loss of time between the processes. The hammers are of the 2ewt. size, but other sizes are constructed on the same principle, with ’selfacting or hand-worked valve gear, and with or without food levers, the latter not being usually fitted to the larger sizes. Three, or even more, hammers can be put together in the manner described, when desired.