Although C. E. Dolbear's father, A. E. Dolbear, had patented a wireless telephone using induction in 1882, that system had not proved practical. The demonstration reported here was essentially an application of Willoughby Smith's Method of wireless telegraphy, using electrical currents transmitted through the water, which had been successfully tested over short distances in Great Britain. This form of "wireless" did not involve radio signals, and despite the enthusiastic endorsements, turned out to be an inferior approach compared to radio transmissions.
New York World Sunday Magazine, May 8, 1898, pages 25, 34:

W. J. Clarke sendingThos. Edison, Jr. receiving
 BY  CAPT.  F.  RODGERS,  U. S. N.
Presi dent  of  the  Board  of  Inspection  and  Survey.
THE experiment of the New York World in submarine telegraphy as described to me, I believe may be developed to such an extent in naval patrol work and off-shore communication as to be of great importance in connection with coast defense.
Comm ander  of  the  Department  of  the  East,  Governor's  Island.
   This is very interesting and highly important. I am obliged for the courtesy which prompted such speedy conveyance of the intelligence gained through these experiments.
Chief  Electrician  of  the  Commercial  Cable  Company.
THE results of the experiment in submarine wireless telegraphy conducted by the Sunday World certainly show that the principle employed is sound. That results may be obtained at comparatively short distances up to three miles or so, has been proved.
Depart ment  Signal  Officer  in  charge  of  the  Submarine  Mining  of  New  York  Harbor,  and  Instructor  of  Electricity  at  the  United  States  Artillery  School,  Fort  Monroe.
THIS experiment is most important and timely. Of course, what the Government, and more particularly the Navy Department, wants is such a means of communicating with ships, especially as it will work as well in darkness or fog as at any other time. I certainly hope this matter will be pushed. The authorities at Washington will be apprised of it undoubtedly. Experiments have been conducted under my direction in Fort Monroe.
    Tests have also been made in wireless telephony, but not under water. I wish I had been able to witness the experiments conducted by Messrs. Edison, Clarke, Cuttriss and Lowenthal. The enterprise will certainly meet with hearty approbation from those who know what wireless submarine telegraphy will accomplish. Personally I am most eager to see this matter pushed, having been sent abroad to look into it and see what Preece, Marconi and others have done in this direction.
    It is doubtful whether telephoning can be done in this way; but if telegraphing can be done from land to ships at sea without wires or visible signals, a wonderful stride forward will have been taken.

Editor  of  the  Electrical  Review.
THE Sunday World's experiment in submarine telegraphy, which I witnessed off Sailors' Snug Harbor, was a very interesting work and was certainly a laudable enterprise on the part of the paper. It is a great thing for a big newspaper to encourage work in electricity and other scientific fields, especially when there is a chance of the results being of practical value to the Government. The results obtained were most encouraging.

 BY  W.  J.  CLARKE,
Invent or  and  Noted  Experimenter  in  Atmospheric  Wireless  Telegraphy.
THE Sunday World's demonstration of the working of a system of submarine signalling without the use of direct wire connexion was cleverly conducted by those in charge and seemed to be entirely successful. It is possible that this system may be improved in such a manner as to be of great practical value.
Inventor  and  Electrical  Expert.
THIS experiment has been an unqualified success. We heard the Morse signals distinctly as long as the boat was within range of the electric waves. Commencing from the Staten Island shore we worked further and further away from the base line--that is, the points on shore where the two copper plates were submerged and connected by a wire running along the shore--almost over to the New Jersey shore.
    Of course, if the principle held true to this decree, it is chiefly a matter of strengthening, extending and improving the plant in order to demonstrate its practical value on a large scale.
    Marconi and Preece abroad and Mr. Clarke in New York have been working on the idea, and the latter has made some clever instruments. The submarine feature of wireless telegraphy is the new and indefinitely productive feature now made manifest. The next step will be to study out the way to transmit, as well as receive, messages from boat to boat and boat to shore. It is especially important at this time, when the means of communication from the United States to one of its squadrons off shore, say in the neighborhood of Havana, is pre-eminently desirable.
    Let the practical, commercial advantages of this means of communication be shown and the value of telegraphy will be enormously increased.

Associ ate  Editor  of  the  Electrical  Engineer.
THE experiment to-day struck me as particularly valuable in that it showed how the simplest, cheapest kind of a plant will enable those on shore to communicate with those off shore. Delicate and complicated instruments have been made for use in wireless telegraphy, but these are not often obtainable, and the idea that if a ship's captain can be told that if he carries a simple telephone receiver parties on shore having merely a couple of copper plates and a telegraph key can send him information or instruction is most engrossing.
    Recently it has been my business to look into this matter and I was greatly gratified to be one of those invited to observe Mr. Dolbear's experiments. The World and Mr. Dolbear have every reason to feel elated over the developments made to-day.
    After the "grounding" of the two wires attached to the telephone receiver on board, one by means of the copper plate thrown over the stern and the other by attaching it to the condensing apparatus, the copper intake pipe, which extended through the bottom of the boat, the clicking of the code message became distinct enough for all practical purposes.
    The hope of electricians to bring about telegraphic communication between vessels at sea and distant shores seems about to be realized. Soon the "transmitter" and "receiver" will be deemed essential on board every kind of craft sailing the highways of commerce.
    The Bureau of Naval Intelligence and the Engineering Department of the army should be told of this and their bright young men set to work to perfect the idea. It is so simple and so easily carried out that valuable ends could be served by thorough experimentation and installing plants before the Hispano-American war is ended.

WIRELESS submarine telegraphy is the latest electrical wonder. The practicability of sending telegraphic messages from shore far out into the ocean, without a wire connection between the sender and receiver, has been proved.
    The feat has been successfully accomplished under the auspices of the Sunday World.
    All that remains to be done now is to put the principles employed into practical commercial or governmental use and to devise proper methods whereby the distance to which the messages may be carried may be increased indefinitely.
    The credit for this important scientific achievement belongs to Mr. C. E. Dolbear, of Boston. Mr. Dolbear, although he is still in his twenties, is a man of advanced ideas, and has earned for himself an enviable place among electrical experts. He is the son of Prof. A. E. Dolbear, of Tufts College, a noted electrician and inventor.
    Young Mr. Dolbear came to New York a few days ago especially to inform the Sunday World of a scheme he had conceived for wireless submarine telegraphy, and offering to demonstrate his theories to the extent of telegraphing from the United States coast to Cuba.
    Realizing the importance of Mr. Dolbear's statements and of the results if wireless telegraphy could be established between Florida and the American fleet off Havana during the present international crisis, the Sunday World furnished him with all the facilities necessary for conducting his preliminary experiments.
    The strip of salt water known as Kill von Kull, between the New Jersey and Staten Island shores, was selected as the most desirable location for the initial test.
    A rocky ledge running in an unbroken line for about 1,600 feet north of the railway station at Sailors' Snug Harbor formed an ideal spot where wires and instruments were in little danger of being molested.
    The principle of Mr. Dolbear's system of submarine wireless telegraphy is exceedingly simple. In a nutshell it is the reading of radiating electric currents as they pass in circuit from one submerged copper plate to another, the two being connected by an insulated wire. The connecting wire may be either under water or run along the shore, the essential point being the submersion of the end plates.
    The wire is cut and an electric battery inserted for the purpose of furnishing the necessary current. Then the wire is cut again, and the transmitter completed by the insertion of a Morse telegraph key.
    These are connected so that the current passes through the water from one terminal to the other on its road from the battery and back. When the key is pressed the circuit is from the battery, through the key, through the connecting part of the wire to the water, through the water to the other terminal and thence back to the battery through
    A current passing through a conductor does not go in a straight line to the other end of the conductor, but spreads out in radiating rays, permeating the whole conducting material. Thus a body of water acting as an electrical conductor between two points will he permeated in all directions between those points.
    Take a straight bar magnet, a fine piece of paper and some iron filings. Lay the magnet on a table, place the paper horizontally on top of it and scatter the iron fillings evenly over the paper, tapping it gently, and the filings will distribute themselves in the same way that this current distributes itself in water.
    On this principle an impulse sent through a shore wire fifty miles long might be felt and registered fifty miles from shore. That the waves of electrical disturbance actually radiate in that proportion to the length of the shore wire Mr. Dolbear claims, and he has proved it.
    By means of a receiver dropped into the water at any point within the base of the radiating current, the message or signal being given on shore may be plainly read. For very long distances a galvanometer, an electrical registering apparatus ot almost inconceivable sensitiveness, such as are used for taking messages from oceanic cables, would be used; but for the purpose of Mr. Dolbear's experiments thus far an ordinary telephone receiver, with its resistance greatly reduced, has been found sufficient.
    To the telephone receiver, connected by insulated wires, are two copper collecting plates. These plates being dropped into the water as nearly parallel as possible to the wire on shore, the opening and closing of the first circuit can be distinctly heard in the telephone receiver, for a part of the current will pass from one plate up the wire and into the receiver, through the receiver and out through the other plate.
    No matter at what point within the radius of the circuit the plates of the receiving apparatus are dropped overboard, the message may be read.
    For four days Mr. Dolbear, assisted by representatives of the Sunday World, worked, setting up and experimenting with different apparatus to determine what was most effective.
    At the point selected for the experiments the Kill von Kull is a quarter of a mile or more across. Fifteen hundred feet of insulated No. 14 copper wire were stretched along the shore, the ends, with their fifteen-inch copper plates, being submerged.
    The first test of the system showed clearly that the principle upon which it worked was sound. There were results; but, like all first experiments, they were not entirely satisfactory. When a thing is right in theory it is only a question of time when a genius like Mr. Dolbear will make it practical.
    Having been able to hear faintly the first message sent over the wire, it was only a question of making slight improvements in the plant, like increasing the power of the battery (which, at the end, contained but twelve volts), decreasing the resistance in the receiver, etc.'
    By last Wednesday evening the apparatus was in splendid working order and the Sunday World sent invitations to a committee of well-known and influential electricians to witness the experiments in wireless submarine telegraphy on the following day. The invitations were readily accepted.
    The party that embarked on the Sunday World tugboat Thursday morning for the Kill von Kull consisted of;
    Messrs. Thomas A. Edison, Jr., inventor and electrical expert; W. J. Clarke, noted inventor of atmospheric wireless telegraphy apparatus and demonstrator of wireless telegraphy in the electrical show, Madison Square Garden; Charles Cuttriss, chief electrician of the Commercial Cable Company; Charles W. Price, editor of the Electrical Review; Max Lowenthal, associate editor of the Electrical Engineer; O. S. Burr and William H. Holzer, electricians in the office of Thomas A. Edison, jr., and for many years associated with the elder Edison; and C. E. Dolbear.
    From the tug Mr. Clarke, Mr. Lowenthal and Mr. Dolbear went ashore in a rowboat to examine the simple system and make sure that there was nothing out of order. It was found that the copper plate had been stolen from one end of the shore wire. A bundle of rusty telegraph wire was [portion missing] operated the telegraph key while Messrs. Lowenthal and Dolbear went out a short way from shore in the rowboat and made the first test. This was highly successful. Each tick of the key could be heard in the telephone receiver with marvellous distinctness.
    There was clearly no need of testing further in the rowboat, so the receiver was put aboard the Sunday World's tug in midstream.
    Tests were then made at four points, the distance from the shore wire being constantly increased until the opposite shore was nearly reached. At that point the tug was 1,500 feet from the Staten Island shore--the length of the transmitter wire--if not further.
    Even at that comparatively great distance each click of the key as Morse telegraph signals were sounded was distinctly heard by the interested listeners on the tug as they passed the receiver from one to the other and discussed the importance and possibilities of the wireless system they were seeing so effectively demonstrated.
    To prove that any metallic boat, a steel or copper bottomed battle-ship, for instance, would require but one plate to be thrown into the water, Mr. Dolbear attached one end of his receiver wire to a portion of the tug's engine. Thus he got a direct connection with the water through a copper keel condenser terminating in copper pipes along the bottom of the boat. This took the place of one of the plates and served the purpose even better than the small plate had.
    Wireless submarine telegraphy had [portion missing] Sunday World for having so generously encouraged and aided an important scientific discovery.
    What was done last Thursday at Kill von Kull is but a taste of the vast possibilities of submarine wireless telegraphy. It opened the way to a vast and important, practically untried, field of electrical work.
    Through these experiments the Sunday World is glad to be able to make a valuable suggestion to the United States Government. In this time of international trouble it is of the greatest importance to keep in communication with our warships at sea, which can now only be done at great expense and loss of time by despatch boats.
    Wireless submarine telegraphy conducted on the basis of the Sunday World's experiments may solve the problem.
    It may readily be seen what a tremendous advantage to the government it would be to be in instant communication with the blockading squadron in Havana Harbor. If the wireless submarine telegraph system works proportionately as well for long distances as it does for short distances there is no reason why such communication should not be established. It has already been proposed to the government.
    The plan is to lay about a hundred miles of strong insulated wire along the Florida Keys, the ends being about equal distances from Key West. The radiating electric currents from such a wire would easily reach to Havana Harbor.
    "I am confidant [portion missing] time. It would be a great thing for a commander to simply drop a couple of big copper plates or a single plate overboard from his vessel and pick right out of the ocean depths his instructions from Washington. I am convinced of the feasibility of the scheme and am patriot enough to be anxious to have it tried.
    "Wireless submarine telegraphy will work both ways. Messages may be sent from vessels on the ocean. All that is necessary is to stretch a wire from the ship equalling the distance from her to land and running parallel with the shore. This could be done by trailing an anchored wire behind the ship or by sending small boats with wire running out from her in either direction parallel with the shore. It does not matter at what point the battery and telegraph key are placed.
    "We have undeniably demonstrated this principle of wireless telegraphy to be sound and I believe it will be of great value to mankind in many ways. For instance it might be used effectively in coast defense work by enabling patrol boats to telegraph to the shore what is going on within sight of them when fifty or a hundred miles out at sea.
    "It would be practicable to have the entire coast wired with relays fifty or a hundred miles long; a patrol boat to each relay ready to telegraph any important news to the shore without the use of wire.
    "The system would be practical [portion missing]
Use in the Florida Keys