SCIENCE SIFTINGS

New Zealand Tablet, Volume LI, Issue 4, 24 January 1924, Page 54

SCIENCE SIFTINGS

By ~VOLT’

Marvels of the Magnet.

How many people, who as children took delight iff the antics of a pin on the end of a magnet, realised that one day this toy would become one of the greatest factors in industrial progress? The origin of the. electric magnet is a romantic story, and one which is a tribute to British brains and endeavor. It was at Sheffield, in 1902, that the first really successful lifting-magnet was produced. To-day they are in use in all the great workshops of the world. N The trouble occasioned in, stacking steel rails, girders,, and similar articles led a Sheffield firm to start experiments. They sought primarily a means of 1 saving time and labor, and various prominent engineers set to work to solve the difficulty. Someone thought of the magnet, then a toy. It had been tried before without success, but that was no reason Why another attempt should not be made with it. Energies were thereupon turned in this direction. Time and time again failure had to be admitted. Then at last an appliance was devised which, under the name of the.“pot” magnet, was brought into use. Here, again, success was only partial, but in this case the fault lay not so much in the ideaindeed, this idea was the basis of the later successful modelsbut rather in the design. Soon afterwards another model was produced which had the desired results, and after considerable experimenting was brought still nearer to perfection. And as the years passed, more and more improvements were brought to bear until, finally, the up-to-date and efficient electric magnet of to-day was produced. The electric magnet, of course, is different 1 from the magnet as we know it. The latest type comprises a circular plate known as the bumping-plate, formed of non-magnetic and extremely strong and durable metal. Manganese steel is the best medium for this face plate, arid it takes all the humps, jars, and shocks caused by the magnet coming into violent contact with the load to be handled. Electric energy is induced by means of coils. $ The feats performed by some of these magnets are wonderful, and very great weights may be lifted with ease. An instrument weighing only 15cwt itself is capable of lifting a load of eight tons, while at a recent demonstration a steel plate on which were twelve workmen was quite comifartably raised. As for quickness, one magnet recently was found to do in seven minutes work which had occupied the time of four men for five hours. But perhaps the greatest wonder associated with the magnet is its power of reducing bulk to scrap, a process which in the past entailed much time and labor. 9 What the magnet does is this: It lifts up a great ball, of solid iron or steel, and when this has been raised over the material which is to be scrapped,* the electric current is switched off and the ball descends with crushing force upon the objects beneath it.