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been making, and I think you will be interested to learn that he has successfully transmitted 130 horse power over eighty-four miles of bare copper wire, supported upon our special insulators; the length of the circuits being eighty-four miles, the conditions are of course such as we should encounter in transmission over forty-two miles. The result was obtained by connecting up in series the respective circuits from the power plant to the town of Pomona and the city of San Bernardino. About 3200 insulators supported the conductor carrying 10,000 volts, and the fact that this was done without the slightest evidence of break-down was noteworthy and important." Since then on some of the Western lines 20,000 volts have been considered moderately low voltage, and 40,000 volts have been used successfully, and this all since the year in which bids were first asked for polyphase alternating-current dynamos under stated conditions by the Cataract Construction Company for the Niagara Falls Power Company at Niagara.

Mr. Edward D. Adams, the president of the Cataract Construction Company, to whom the above letter was addressed, was thoroughly alive to the advantage of the use of the alternating.current system in 1890, but in financiering the great development at Niagara Falls he held his mind open for truth, which he steadily pursued from the beginning, sustained by those interested with him, regardless of his own pecuniary interest and that of his personal friends.

My own interest in electricity began in early boyhood. As soon as I was able I followed the discoveries of Faraday and others experimentally, using instruments made by myself for the purpose. From 1846 to nearly 1849 I was engaged to superintend rolling iron and making the telegraph wire that was used in the first lines established west of the Allegheny Mountains. Keeping in touch with progress of the uses to which electricity has been applied, I have noted how powerfully the growing needs excite the inventive faculty of those engaged in any one branch of science; in general, also, the slow application to actual practice of knowledge given to the world by men seeking truth and laying the foundation of exact scientific methods. Our modern knowledge of thermodynamics does not express what was used to perfect the steam engine, as the best results and the greatest advance in the use of steam came before the students of thermo-dynamics gave us the modern text-book on the theory of steam. So it is with the trans

mission of energy by electricity: beyond the possession of useful knowledge, actual practice and the attempt to accomplish results will yet need many venturesome efforts.

In utilizing the power of Niagara Falls large units of power have been shown to be economical. A single dynamo built to yield 5000 electrical horse power has yielded 5600 electrical horse power without sign of overload. The wonderful efficiency of these machines, which have a loss of less than two and one-half per cent., has established the superiority of electrical transmission of power, and proved it to be more economical than any of the usual methods of transmission by material in motion; that is to say, by shafting, belting or compressed air, etc. All such methods involve great frictional loss. When a steam engine is attached directly to a dynamo, the electrical output of the dynamo, measured by modern instruments of precision, is known to be more reliable as an ir.di. cation of the power produced by the combustion of a given amount of coal than any ordinary method of indicating the power of a steam engine to determine the horse power per pound of coal burned. Large factories, such as the Baldwin Locomotive Works, have recognized the economy of generating electricity by steam and transmitting it to the various machines or groups of machines in use, to which electric motors are applied, thus dispensing with long lines of shafting. How far electricity can be transmitted from the turbines at Niagara Falls with profit remains yet to be determined. The actual economy obtained by transmission to Buffalo, say a distance of twenty-two miles, is so much beyond what was predicated as possible in 1890, or even 1893, that no one can venture to say what will be forthcoming in the near future. With electricity it is very much as it was with railroads; fifteen miles

per hour was thought to be a dangerous speed when locomotives began to supersede the stage coach. Those who travel now hope for an improvement that will lead to a higher rate of speed than we are now accustomed to. So it is with electricity by overhead lines of transmission. One thousand volts is no less dangerous than 11,000 volts on the Buffalo line, or 20,000 or 30,000 on some of the air lines in this country.

The question of underground transmission calls for a high quality of insulating material or method of preventing leakage, and of providing means of dissipating the heat that must result from any loss due to resistance in the conducting material used.

Copper is, of the available materials, the best conductor and the cheapest. The price of aluminum, however, owing to the cheap power used in its manufacture, has fallen from five dollars per pound to twenty-five cents per pound. Pure aluminum, properly alloyed with a metal that will increase its strength without decreasing its conducting quality, renders it possible at the present time for aluminum conductors to be offered at exactly the same price per mile as copper, with the added advantage of allowing the poles supporting the line to be placed much farther apart, thus using fewer insulators and decreasing the cost of the line; also insuring more economy in transmission, as there is less leakage, due to the diminished number of supports, all of which will be weak points in the transmitting system. The increased area required for the lighter metal, resulting in a larger radiating surface, is favorable also to the dissipation of the heat engendered by the resistance in the line, as whatever energy is lost in such transmission assumes the form of heat energy.

What can this or any other learned Society do to help in the promotion of the knowledge of electricity applied to the use of man? It is a matter of great importance to those interested in the work of this Society that they recognize the necessity of exerting themselves to carry out the intent of its founder in promoting useful knowledge. We must try to induce the members and others to make use of the advantages that the Society possesses in disseminating useful knowledge through its publications, and to make this building and these rooms the place for the discussion of subjects of practical as well as theoretical importance in the same direction, on the lines so earnestly followed by its founder, who tried to bring together representative men of varied attainments and to have them submit papers for discussion.

In my efforts to interest members in our work in the direction of the subject of this discourse, and to have them submit papers for discussion, I have been met, first, with the excuse of want of time for the preparation of matter; second, the desire of most specialists to contribute to the societies devoted to their specialties; third, to the fact that there are so many periodicals for each special department of science ready and eager to obtain, even to pay for, copy, and in the case of electricity as applied to the service of man many of the professors of physics in colleges, specialists besides those on the staffs of the great manufacturing companies, are re

tained in the interest of such companies, and in some cases are even discouraged from making public what for a time can be used to advantage in a commercial way and classed among the trade secrets. I speak knowingly on this subject, for the first question that was asked me in 1889, before I was solicited to report on the subject of transmission of power by electricity, was whether I was retained in the interest of any electric company. The fact that patent litigation has played so important a part in the development of electricity is also to be taken into account when an effort is made to awaken debate on subjects that should be of special interest in the Society founded by the early electrician, Benjamin Franklin. Many men are loath to commit themselves in debate that may in a short time be taken hold of by patent attorneys. The commercial aspect of scientific advance is too important to be ignored ; we must therefore, as members of the American Philosophical Society, as far as we can, induce others to assist in the work of the Society by showing a willingness to take an active part in the meetings that are held in this room, and by early publication of matter submitted give precedent in publication to those who lay claims to priority of discovery.

Slated Meeting, April 21, 1899.

Vice-President SELLERS in the Chair.

Present, 17 members.

The Curators announced that, in accordance with a resolu. tion of the Society, the Carthaginian tombstone in its possession had been photographed, and exhibited a blue print of same (see accompanying figure, page 72).

The death of Sir Monier-Monier Williams, of London, England, April 11, 1899, who was elected a member December 17, 1886, was announced.

Dr. Stellwagen made a verbal communication to the Society in regard to a tombstone presented by Commodore Stellwagen,

on behalf of Mr. Perry, which was brought from Carthage. He said:

It was in the spring of 1864, if my memory serves me correctly, that, at the urgent request of the Consul-General of the United States, Mr. Amos Perry, the U. S. S. “Constellation,” of which I was an officer, paid a visit to the Bey of Tunis, as trouble with the Bedouins had caused alarm among the European residents.

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The Consul requested my father, Captain Henry S. Stellwagen, U. S. Navy, to bring two gravestones or stelæ to this country and send one each to scientific bodies in Philadelphia and New York. The one exhibited here this evening was first given into the care of the Academy of Natural Sciences, but afterwards, at the suggestion of an officer of that body, it was sent to the American Philosophical Society.

At the time of our visit the ruins of Carthage were so completely

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