Science Siftings

New Zealand Tablet, 26 November 1914, Page 53

Science Siftings

Bt ‘ Volt/

Fire-Resisting Doors. For fire-resisting doors armoured wood is taking the place of iron in many warehouses and factories. The armoured fire door is made of several thicknesses of seasoned pine boards, planed, tongued, and grooved, and well nailed together, and is covered with tinnedsteel sheets fitting close to the wood. Several hours of the fiercest heat simply carbonises, the outer layer of wood to the depth of a fraction of an inch. The door remains in place, and is not, as the iron often is, warped and torn from its fastenings.

Moving a Mountain.

Moving a hill even a few feet proved too big a job for Mohammed, but to-day, in California, a mountain is being shipped three . thousand miles to Pennsylvania. Situated at Lompoc, Santa Barbara County, this mountain is really a heap of millions and millions of tiny decomposed sea shells. It is sold as 1 infusorial earth/ and has a high value for insulating purposes and for jewellers’ grinding pastes. The earth is white in color, fluffy in consistency, and exceedingly fine in grain. Fifteen cars containing fifty tons each are moved monthly. When the last car goes out, it will be possible to tell precisely: how much the mountain weighed.

An Electrical Towel.

One of the newest sanitary devices for use in public or semi-public lavatories, like those in hotels and factories, is an electrical substitute for the towel. This electric hand-drier is in appearance merely a sheet-iron case, with an opening in the top. In using it, you put your hands in the opening, and with your foot press a pedal at the bottom of the case. The pedal starts a blower, which in its turn forces air through the electric

heater, and Sends a warm current of it over your hands. Your hands will, it is said, be thoroughly dry in from 30 to 40 seconds—much less time than anyone ordinarily' needs in order to dry them with a towel. The hand drier is quite sanitary, for in using it you do not have t 5 touch any part of it.

Radium and Lightning.

Radium has been discovered vastly to improve lightning rods in their protection of buildings during thunderstorms. Of course the enormous cost of radium prevents any practical use of the fact as yet. But there is a very fair possibility that the information gained in this way will lead to a new form of lightning rod which will be more efficient or that further experiments will show that a tiny quantity of radium at a reason-: able cost will improve the protection. The purpose of lightning rods, of course, is to catch the electrical currents in the air during a storm and lead them safely into the ground instead of allowing the lightning to pick its own course down through a house qr church steeple, and their use is based on the principle that a metal rod will give the electricity a smoother path of less resistance than ordinary building material. The whole trouble with lightning rods now is that, though 'they can be made to do the trick if the electrical discharge is near them, there is no way to lead electricity through the air to the rod. Radium will do this part of the work, as has been demonstrated in scientific experiments. Two milligrams of radium on the end of a rod made the air a considerable distance away a vastly better conductor., Thus any electrical discharge within several yards of the rod had a path open for it along the radium rays to the rod and then down the rod to the earth.