The New Subway - Its Electrical Equipment and System Criticized Severely by Mr. Tesla

To the editor of The Sun — Sir: I would not disturb the hymn sung by the press in praise of the subway had it not occurred to me that just these few fugitive moments of ecstasy offer the best opportunity for pointing out the necessity of its speedy re-equipment. My idea is by no means as odd as it must at first appear to your readers. Permit me to explain.

Electrical power transmission has been my specialty for many years. After the general adoption of my alternating system of distribution, popularly known as the "two, three, multi, or poly phase," I turned my attention exclusively to currents of high tension and devised a scheme of artificial insulation by power, permitting an indefinite extension of the distance of transmission and doing away altogether with the loss in the mains. Finally, through a series of improvements, I arrived at my high potential system, dispensing with wires, in which I have carried the arc of electrical energy transmission well toward its highest technical perfection and capacity of application. These inventions, abolishing all barriers to electrical development, will soon sweep the world with irresistible force.

Naturally enough, I have been intensely interested in this great project, in the city of my home, from its very inception, and have devoted much thought to the best means to employ. The tunnel itself I have never seen and do not know its location. It must be a fine piece of engineering. I am compelled to confess to the same ignorance as regards the power house. The Rapid Transit company has never asked me for any expert advice or suggestion and I have never been invited to examine any part of the work. It is true that my "three phase" system with my "rotary converters" has been adopted, but it is precisely because of this that a change will be necessary in the near future. This combination of alternating and direct current should not have been employed. It represents the state of the art of more than ten years ago. In the power house three phase dynamos are Installed. The electro-motive force of the currents is raised by "static transformers." The high tension currents operate in each of the sections of the road a "rotating transformer," in this case one of my three phase synchronous motors having its field excited by and generating direct currents, which in turn, actuate the motors on the cars.

Now, this plan, while operative, is for a great many reasons objectionable, more so in this particular instance. The subway problem was peculiar. The length of the circuits was insignificant. The facilities for placing and insulating the mains were great. Financial limitations, which usually hamper an electrical enterprise, did not exist. There was money to burn. The quickness of travel, the safety of the public and of the adjacent property were the dominating requirements. These have not been properly met. A mistake was made in not asking the electric companies to furnish the best instead of the cheapest equipment.

But it is better to mend late than never. Ignoring the improvements which might be made in the power house, the mains should be insulated artificially by refrigeration. This would save the energy which is now lost in the mains and money besides. More than this, it would insure complete safety against any breakdown of the insulation, which, however, would be self-restorative. The "rotating transformers," introducing many elements of incertitude and danger, should be done away with and "static transformers," if necessary, installed in the sub-stations. Direct currents, which are a constant menace to life and property, despite subdivision, should be most certainly avoided. Motors of this kind, with their brushes and commutators, sparks, oopper dust, nitric acid and what not, are not suitable for so important a thoroughfare, and should be replaced by my "induction motors" without brushes and commutators, and perfectly free from the innumerable troubles these devices entail. It I would be advisable also to employ a greater number of correspondingly smaller motors on each car. This would be, in my opinion, an entirely safe, economical, and in the long run the cheapest apparatus, which could be taxed, without the slightest risk, in the hours of rush, to its utmost capacity, and which, if properly constructed, should last a century.

To conclude, as I examine the equipment of the subway, I find that about all to be preserved would be Mr. Belmont's beautiful car, this as a corpus delicti. The changes suggested will have to be made sooner or later, and I am quite earnest in recommending an immediate appropriation and commencement of this work of reconstruction without delay, else Philadelphia will have an underground railway several decades ahead of ours.

NEW YORK, Oct. 30.
N. TESLA.