Insulation By Cold

The discoveries and inventions of Nikola Tesla have of late been noticeable more for their ingenuity than for their practicality. Whether the latest belongs to this category or not, it is not our place to determine. It is a method for the insulation of electric conductors by immersing them in some medium that insulates when frozen, and by then keeping this below the freezing-point. Mr. Tesla thus describes his invention in a newspaper interview:

"Imagine a great trough extending, if you wish, across the continent. It must contain a quantity of water or some other substance which will freeze. From my experiments I judge that sawdust and water will prove most effective. For the purpose of transmitting the current long distances I shall use a thin metal tube capable of resisting three hundred pounds pressure to the square inch. This tube will be submerged in the subIstance which I intend to freeze.

"In the whole discovery the most interesting feature is the method I have devised for freezing the material in the trough. Five or six feet below the surface the ground itself is very cold. Here the trough would be buried. Through the tube there will then be forced a current of gas — probably hydrogen — reduced to a temperature of minus 200 degrees or thereabouts.

"This, under ordinary circumstances, will be sufficient to freeze the material surrounding the tube in the trough, and also to neutralize the heat which would be generated by the electricity."

Referring to the advantages that might be derived from this new system of insulation the inventor said:

"It has been known since the days of Faraday that an electrical current can not break through an insulation of ice. My success lies in discovering how practically to apply this truth. To show of what gigantic worth it may be needs but a moment. Grant that the invention has, as I believe, given to the world an almost perfect insulator, immediately there follow results which will directly or indirectly affect every manufacturing industry which in any way uses electricity.

"This will follow from the fact that no electricity will be lost in transmission. The cost of the new insulation will in the end be cheaper than that now used, and so it follows that the electricity which is to be utilized in a thousand different ways can be produced at a less cost. To telephone and telegraph companies, therefore, you see that my invention will be indispensable.

"Water-power converted into electricity can by the new method of insulation be carried thousands of miles. At present the loss of electricity due to unsatisfactory insulation makes this impossible. I have been considering the possibility of carrying the power of Niagara to this city, and find that it can be done with a loss of not more than one-half per cent. to one per cent.

"For the first time in history a power will be used for insulation instead of a property. Deaths from contact with exposed wires will be prevented by the new method. The increase in the speed of exchange of telephone and telegraph messages will be pronounced after the adoption of my discovery.

"These are the important changes in the electrical world which will be wrought by this invention. There will be also innumerable indirect results."

Commenting upo. all this Electricity (August 22) says editorially:

"This system of insulation, as will readily be seen, would entail the digging of trenches and laying of tubing, to say nothing of forcing a current of gas through the whole system, which, over a long distance, would entail an enormous initial expenditure of money. This would seem to be the principal objection to the system and one which would prohibit its adoption in carrying power to localities situated a hundred or more miles distant, where fuel could be obtained at reasonable prices. That such a system, if found practicable, would have its field of usefulness there is not the slightest doubt, but that field would be limited or not sufficiently extensive to warrant insulation manufacturers looking about for some other means of earning an honest living."