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1900] MARINE REVIEW. 15 for an instant by the tap of the trembler and immediately reestablished by the electrical surgings, and therefore the relay tapper and telegraph instrument are again actuated, and so on until the oscillations from the radiator cease. The practical result is that the receiver is actuated for a time equal to that during which the key is pressed at the transmitting station. For each signal, however short, the armatures of the relay and tapper perform some very rapid vibrations dependent on each other.. For it is the action of the relay which starts the tapper, but the latter by its action interrupts the relay. The armature of the Morse recording in- strument, being rather heavy and possessing a comparatively large in- Fi6.R ertia, cannot follow the very rapid vibrations of the tongue of the relay, but remains down all the time during which the rapidly intermittent action of the receiver lasts. In this way the armature of the inker gives a practically exact reproduction of the movements of the key at the trans- mitting end, dashes coming out as dashes and dots as dots." The foregoing is a general description of the principal apparatus used by Mr. Marconi in his system of wireless telegraphy. It is im- practicable to give the many improvements that have been made in the instruments themselves--and are still being made--or to enter into tech- nical details. The principle remains the same, and while the system is far beyond the experimental stage, it is as yet in its infancy and new results are constantly developing and perfecting its application. Mr. Marconi has proved by experiment that up to certain limits, given a parity of conditions, the distance to which effective signaling extends varies approximately as the square of the height of the rod. A vertical wire 20 feet long at the transmitter and receiver is sufficient for communicat- ing one mile, 40 feet at each end for four miles, 80 feet for 16 miles, and so on. Theoretically, there seems to be no limit to its range, given sparks powerful enough and conductors high enough. Practically, however, there are numerous obstacles. Various applications of the Marconi system have occurred and have met with uniform success. It played an important part in recent British naval maneuvers and proved so satisfactory to the British Admiralty that a complete outfit has been supplied to the Defiance, the torpedo school ship at Davenport, for further experiments by naval officers. More recent still is the part played by this system in reporting the international yacht race between the Columbia and Shamrock and while the distances covered were much less than those already attained, it was the first prac- tical demonstration of the possibilities and usefulness of wireless tele- graphy in this country. The speed of signaling by this system appears to be from twelve to eighteen words a minute. It is stated, however, that a speed of twenty-two words has been attained, and this may doubtless be very materially increased. : Hitherto one of the chief objections to the use of wireless telegraphy has been the impossibility of concentrating the message, or in other words, to cut out a station and prevent a message from being received at other stations haying installations within the radius of that for which the message was intended. Mr. Marconi claims to have an arrangement by which this can be overcome. In some experiments carried out on board the French dispatch 'boat Ibis, having on board a French commis- sion, messages sent from the. Ibis to the South Foreland were concen- trated there, the East Goodwin light-ship being cut_out. Similarly mes- sages were sent to the light-ship, while the South Foreland was cut out. As a further test messages were sent simultaneously from Boulogne and the light-ship to the South Foreland, where the Boulogne message only was taken by the receiver, the other being cut out at will, This possi- bility is as yet, however, in its experimental stage, and at present it may be assumed that but one transmitter can be operated in the same neigh- borhood. The tests thus far made and the existing Marconi installations demonstrate the practicability of wireless telegraphy. It is stated that signals are now transmitted over 100 miles. TRIALS IN OUR OWN NAVY. At the conclusion of the yacht races Mr. Marconi conducted a series of experiments for the navy department under varying conditions with a view of testing its value for service use. For this purpose, sets of ap- paratus were installed on board the Massachusetts and New York and a third set on shore at the Highlands of Navesink. The first tests were at short distances while the two ships were at anchor in North river. These were followed by experiments over varying distances, the Massa- chusetts proceeding to sea, while the New York remained at anchorage in North river. Messages were received by the former all the way to Sandy Hook light-ship, but those sent by the Massachusetts failed to be received on the New York through fault of a poor earth connection on the latter. The New York then anchored 5 miles off Navesink, while the Massachusetts proceeded to sea for distance and interference tests. During the time the Massachusetts was under way messages were ex- changed between her and the New York at intervals of ten minutes, inter- ference messages being sent from Navesink at certain times with the result that when the New York and Navesink stations operated simul- taneously, the Massachusetts received unintelligible signals. The Massa- chusetts and New York communicated up to 36 nautical miles. Advan- tage was taken of a gale to test this system under what would seem- ingly be the most unfavorable conditions. The Massachusetts anchored inside Sandy Hook and the New York in Gravesend bay. Both ships . lowered the sprits to which the vertical wire was attached and hoisted the latter to their mastheads. In spite of wind, rain and fog, communication was perfect. The naval board appointed to conduct the above experi- ments reported as follows: * _ | We respectfully submit the following findings as the result of our investigation of the Marconi system of wireless telegraphy: It is well adapted for use in squadron signaling under conditions of rain, fog, darkness and motion of speed. Wind, rain, fog and other conditions of weather do not affect the transmission through space, but dampness may reduce the range, rapidity and accuracy by impairing the insulation of the aerial wire and the instruments. Darkness has no effect. We have no data. as to the effects of rolling and pitching, but excessive vibration at high speed apparently produced no bad effect on the instru- ments, and we believe the working of the system would be very little affected by the motion of the ship, The accuracy is good within the working ranges. Cipher and important signals may. be repeated back to the sending station, if necessary, to insure absolute accuracy. When ships are close together (less than 400 yards) adjustments, easily made, of the instruments are necessary. The greatest distance that messages, were exchanged with the station at Navesink was 16.5 miles. This distance was exceeded considerably during the yacht races, when a more efficient set of instruments was installed there. The best location of instruments would be below, well protected, in easy communication with the com- manding officer. The spark of the sending coil or of a considerable leak, due to faulty insulation of the sending wire, would be sufficient to ignite an inflammable mixture of gas or other easily lighted matter, but with the direct lead (through air space, if possible) and the high insulation necessary for good work no danger of fire need be apprehended. When two transmitters are sending at the same time all the receiving wires within range receive the impulses from transmitters, and the tapes, al- though unreadable, show unmistakably that such double sending is tak- ing place. In every case, under a great number of varied conditions, the attempted interference was complete. Mr. Marconi, although he stated to the board before these attempts were made that the could prevent inter- ference, never explained how nor made any attempt to demonstrate that it could 'be done. Between large ships (heights of masts 1380 and 140 feet) and a torpedo boat (height of mast 45 feet), across open water, signals can be read up to seven miles on the ship. Communication might be interrupted altogether when tall buildings of iron framing intervene. The rapidity is not greater than twelve words:per minute for skilled oper- ators. The shock from the sending coil of wire may be quite severe and even dangerous to a person with a weak heart. No fatal accidents have been recorded. The liability to accident from lightning has not been as- certained. The sending apparatus and wire would injuriously affect the compass if placed near it. The exact distance is not known and should be determined by experiment. The system is adapted for use on all vessels of the navy, including torpedo boats and small vessels, as patrols, scouts and dispatch boats, but it is impracticable in a small boat.. For landing parties the only feasible method of use would be to erect a,pole on shore and then communicate with the ship. The system-could be adapted to the telegraphic determination of differences of longitude in surveying. The board respectfully recommends that the system be given a trial in the navy." : In a letter to the naval board Mr. Marconi stated that he was unable to give a demonstration of the devices used for preventing inter- ference, and of the means used for tuning or syntonizing the instru- ments, the reason given being that they were not completely patented and protected. It should also be stated that Mr. Miarconi, before con- ducting these experiments, stated that the distance of transmission would not be so great as that obtained during the British naval maneuvers, as the apparatus brought was for the purpose of telegraphing the result of the yacht races, where long-distance transmission was unnecessary. The advantages claimed for this system are its cheapness, and the ease and rapidity with which it can be transported and installed. In the occupation of colonial territory, for 'communication between vessels and the shore or other vessels, the system is invaluable. As the system now stands, the lack of secrecy. its susceptibility to interference, the fact that at best there can be only a limited number of stations within a given radius, and the slowness of transmission, all tend to limit its use to some such purpose as indicated. AT THE HARLAN & HOLLINGSWORTH WORKS, The Harlan & Hollingsworth Co., Wilmington, Del., on Saturday launched from one set of ways three tugs for the Pennsylvania Railroad Co. The boats were the Wilmington, Johnstown and Harrisburg. In the space of 17 minutes from the time the first wedge was driven the last boat struck the water. Dimensions of these tugs are: Length over all, 100 feet; beam, molded, 22 feet; depth, 12 feet 2 inches. A house on the deck of each of the vessels is partitioned off so as to form galley, boiler room, crew's water closet, engine room and cabin. Above this are pilot house, skylight, etc. Engines are of compound type with cylinders of 20 and 40 inches diameter ana 26 inches stroke of piston. There are two Almy water tube boilers in each of the vessels. Other work at this yard is progressing rapidly. The steamer Whit- ney for the Metropolitan Steamship Co. will be launched shortly. The Mannahata, launched last month for the New York & Baltimore Trans- portation Co., will be delivered this month, and the barges for the Rockland & Rockport Lime Co. are being rapidly erected... A new 400- foot steamer, the first of three for the Mallory line, will be laid down on the ways just vacated by the tugs for the Pennsylvania company. A yacht for Mr. Charles Fletcher of Providence, R. I., to be built at this yard, will be one of the handsomest additions to the fleet of 1901, and will be laid down immediately after the launching of the first of the barges for the Rockland & Rockport Lime Co. The steamer Foxhall, undergoing extensive repairs, will be delivered shortly. The steamer Indian of the Boston & Philadelphia Steamship Co.'s fleet, is being lengthened 40 feet. With all these new vessels and a very large amount of car work under way the plant of the Harlan & Hollingsworth Co. is about as busy as it has been at any time for a year past. =e