Although the name of the German firm which provided the arc-transmitter is not mentioned in this review, other reports by the author stated that it was Telefunken equipment.
Electrician and Mechanic, April, 1912, pages 277-280:
EXPERIENCES IN WIRELESS TELEPHONING
AUSTIN C. LESCARBOURA
During the latter part of 1908 and the beginning of the succeeding year, a number of wireless telephone experiments were conducted by several wireless companies, in view of proving the practicability of their respective sets and receive an order for equipment from the United States Signal Corps. The tests were between Fort Hancock, Sandy Hook, N.J., and Fort Wood located on Bedloes Island in New York Bay, the latter being on the same island as the Statue of Liberty. The total distance between the stations was 18 miles, with the high hills of Staten Island separating both. The writer at the time was in the employ of one of the competing concerns, and aided in the operating of the transmitting wireless telephone set at Fort Hancock. The experience, both from a technical and humorous point of view is interesting, and in the following paragraphs, a few incidents and descriptions are faithfully given.
Fort Hancock, as stated before, is located at Sandy Hook, a long and narrow stretch of sandy waste extending into the Atlantic Ocean and forming the lower portion of New York Bay and entrance. In summer the heat is extreme, for the sun heats the sand to a tropical heat, while in winter, the cold wind blows in from the open sea with Arctic vigor. The temperature is usually in one extreme or another, but during several months in the spring and autumn, the weather may be fair at intervals.
On a morning in the latter part of October, 1908, another man and the writer started for Sandy Hook from New York in the U.S.S. Ordnance. This "steamer" in reality is an overgrown and comfortable tug boat, equipped for carrying freight and passengers to the many forts in New York Harbor. After a rough trip, we arrived at 9 o'clock and immediately walked to the wireless station. This station consisted of a two-story concrete structure, with a wooden mast in the rear supporting an umbrella aerial. The wireless apparatus consisted of a 1 k.w. transformer mounted in a cabinet with the spark gap and condensers. A large desk contained the receiving apparatus consisting of a large tuning coil with silicon and electrolytic detectors. The key was mounted on a rubber base, with a long lever passing through a slot and into a tank of oil in the desk, where the contacts were located.
Our telephone set was mounted on a large table with a back board. The transmitting set consisted of ten arc units in series, each unit comprising of a copper cylinder which was filled with water and mounted on a wooden frame; and a large carbon rod held on a long spring. The carbon rods could be adjusted by a thumb screw located at one end, which also contained a large handle, so that all the springs could be pressed down and thus start the arcs if desired. Two sets of five arc lights each were placed at both sides of the table, while the oil condenser was located in the center, in back of a switch for connecting the receiver or transmitter to the aerial and ground. On the backboard, two hot-wire ammeters were mounted, one of these indicating the high-frequency in the aerial circuit, while the other indicated the energy in the oscillation circuit. The third ammeter was of the standard magnetic type, and indicated the amperage consumed by the arcs. The current was furnished by a 500 to 600 volt C.&W. generator, directly connected to a 110-volt, 7 h.p. motor. Suitable field control, enabled us to obtain voltages from 400 to 600 volts. The microphone, which is one of the "missing links" in all wireless telephone sets, consisted of a round enclosed case with a diaphragm in front and an insulated contact in the rear. Having a number of these microphone units, we were able to slip a new one into place whenever necessary, by merely giving the mouthpiece a slight turn, and replacing the old microphone with a new one.
The first morning we arrived, the apparatus had already been delivered and was unpacked in the operating room, only the temporary wiring being necessary. We connected the motor-generator and the regular operator of the station called the power house on the telephone with orders to start up another generator for the peak load to follow. One wire from the generator was then attached to the tin side of a can, and the other wire attached to a voltmeter and then allowed to dip in the can of water. The meter then indicated whether the connections were correct, so that the positive pole could be identified. The meter did not read higher than 125 volts, and for this reason the water resistance had to be inserted. The positive and negative wires were then connected to their proper terminals on the transmitting apparatus. The water having been placed in all the copper cylinders, the arcs were started, and the condenser adjusted. This condenser consisted of 24 stationary and 23 rotary plates, the glass containing jar being filled with paraffin oil. After an hour or more of adjustment and changes, the ammeter in the oscillation circuit indicated that the current was steady. The aerial circuit was then connected to the aerial, and immediately the needles on both ammeters began to flicker again, finally coming to rest after another period of adjustment. The microphone then being slipped into place, the words were shouted into the mouth-piece. At every sound the needles on both ammeters fluctuated, the variation being more pronounced the higher the pitch, and phonograph conversation or music producing the greatest results. After a few minutes of phonograph concert, the needles of the ammeters would become inactive, which signified that the microphone had become "baked" or useless. A wooden stick or other article was then used to hit the microphone case, but having little effect on the ruined carbon grains, another microphone was inserted. From time to time the microphone had to be knocked in order to keep it from "baking," and the best results were noticed when the microphone was continually being turned; which would suggest that a carbon microphone being slowly revolved by a mechanical device would be more suitable to withstand the high amperage, since it is continually moving the carbon grains. At one time a large dog was brought into the operating room and placed on a large box with his head near the mouth-piece. He was finally coaxed into barking, which, judging from the deflection of the ammeters, must have been heard by the stations within our range. This is the first record of a dog "speaking" over a wireless telephone!
On a cold November morning we again set out for Sandy Hook on the same boat as before. On nearing the fort, the writer became worried in failing to see the wires of the aerial. A gale had swept the coast the night before, and it was not impossible that the wires had been blown down. The pole was plainly visible, but no wires could be noticed. Both of us became excited, for we knew that without the aerial, we would have a whole day wasted with nothing to do but to walk around the reservation. However, on reaching a few hundred feet from the fort, we noticed that the wires were still there and that these happened to be of a very small gauge. In fact, we believed at the time that our failure to cover a greater range was due to the inefficient aerial, which was composed of small wire and had but a single wire lead to the aerial from the station. On making the necessary connections, the starting-box lever was moved, but the motor did not start. An instant later the 60-ampere fuse in the cut-out went off, and indicated something wrong. On trying to turn the armature by hand, it was found to be firmly held by the bearings so that it could not turn. This was probably due to the extreme cold, but any way, the application of the blow-torch on the bearings for a few minutes seems to have freed the shaft so that it turned at the moving of the starting-box lever.
There was still more delay in another direction, when we found that the glass jar of the variable condenser had been broken with the extreme cold and that the oil had covered the floor. The plates were thickly coated with dust and the condenser would be unfit for use until thoroughly cleaned and placed in another jar. We substituted another condenser of the same type and started the arcs. After the customary adjusting and dickering, the meters finally came to a reasonable rest, and the phonograph started. After a short while, in which the phonograph was continually playing and only the occasional knocking or replacing of the microphone was found necessary, there suddenly came a slight noise similar to that caused by escaping steam, but just for an instant, and immediately the arcs and ammeters went wrong. It proved to be the short-circuiting of the variable condenser, a spark having jumped between two plates, and a little black dirt appeared between the plates. This dirt is a compound of carbon from the paraffin oil, and conducts the current from one plate to another, thus rendering the condenser useless for high voltage currents. Happily, we still had a large condenser belonging to the Donitz wavemeter, which was inserted in place. It might be stated here, that this condenser, though it had the plates separated only 1/16 in. apart, withstood the potential without breaking down, while condensers with plates spaced 1/8 in. and built in this country were continually breaking down. This illustrates the accuracy of German mechanics, for the plates of the German condensers were perfectly true, which cannot be said of the others.
During the course of the afternoon, a battleship, which was passing Sandy Hook on its journey to the Hudson River where it was to anchor; called the operator and asked him the name of the set being used. On being told, he telegraphed back: "The music is fine, give us some more." We heard later that all the officers on the battleship had been called by the operator to hear the music in the telephone receivers.
In all our tests, between times when the phonograph was not working, the conversation usually ran: "Hello, Hello, Hello Fort Wood, how do you get me now? One, Two, Three, Four, Five," and so on, most of the words being shouted very slowly and drawn out. It is rather a peculiar feeling to be talking into the mouth-piece of a wireless telephone, and not knowing whether the speech is being heard or whether it is not being heard. The phonograph is used the greater portion of the time, for it carries better than the human voice. That afternoon our concert was heard at 20 miles, the Brooklyn Navy Yard operator having listened the greater part of the morning and afternoon. At four o'clock we returned to the boat for New York.
The third and last test of this series, if the writer correctly recollects, occurred in January of 1909. After all the preliminaries, such as the wiring, adjusting, substituting, and swearing, the phonograph was started, and for upwards of an hour we did not think of changing the record. The one playing happened to be, "The Anvil Chorus," from the opera. "Il Trovatore." This selection was played by a band with a number of persons whistling, and proved to be a very effective record for fluctuating the ammeters, which was a desired feature. After an hour had passed with the continual playing of the same record, we shut down the generator and arcs, while the operator listened in to hear whether Fort Wood would call us. Upon calling Fort Wood, he received no reply from that station, but Manhattan Beach (DF) immediately called, and upon being told to go ahead, telegraphed: "For ------ sake change the tune." When asked whether he had received all we had spoken and played, he said that he could get all of it without trouble, but was disgusted with the same record continuously. We did change, and for the rest of the morning played different records. At 12 o'clock, a telegram arrived via the Postal Telegraph station telling us to abandon the tests as the interference was too powerful in the upper bay and while we had been heard clearly at times, the extreme proximity of the other stations completely overcame our signals. We had to wait until 4 o'clock for the boat, so devoted the time to visiting the buildings and looking over the various interesting features of the reservation. A humorous incident, the writer recalls, is the reporting of steamers sighted at Sandy Hook. The two telegraph companies, Postal and Western Union, are located at the end of the Hook, and both have tall buildings resembling lighthouses. The one we visited was maintained by an old time operator who had six wires to handle beside the reporting of the steamships sighted. There is great rivalry between the two companies as to which one reports a steamer first. The old-time operator had erected a few wires from a pole to his telegraph station, and with the aid of the wireless station operator and other local talent had succeeded in constructing a simple receiving set. He would then listen with the telephones placed on his head, and hear the different steamers report to Fire Island, about 40 miles away. Upon the first sign of smoke over the horizon about an hour and a half later, he would immediately telegraph to New York that the steamer was sighted. Meanwhile, the other operator in the other building was straining his eyes through a 5 ft. telescope to get a glimpse at the funnels of the boat. For sometime the competing operator was at a loss to understand how the veteran operator could report the ships before they could even be seen, and on asking him was informed that the operator recognized them by the smoke only! The news finally leaked out, and the wireless was abandoned for the purpose, only the long telescopes being used.
Through these tests the practicability of the wireless telephone was found to be uncertain. Though these tests were performed over three years ago, no definite advancement has been made in the art. The greatest difficulties are in the arc, condenser, and microphone. The arcs will never become practical as they exist at present, for there are periods when the oscillations are perfectly steady, but in the middle of an important conversation, the arcs will suddenly sputter and the words are lost. The condensers are a continual source of worry, and, unless accurately constructed, will break down rapidly. The microphone, likewise, is unreliable, and continually requiring attention. These weak points cause the wireless telephone to be uncertain.
The points to be learned from these tests are: to employ an aerial having a large capacity and many leads to and from the aerial; that a microphone of the carbon grain type with a continuous rotating device will overcome the "baking" to a great extent; that the condenser should be made with rotary plates in oil, and that these plates may be larger and separated by a larger gap to overcome the breaking down as experienced with smaller gaps; that many arcs give greater results than a single arc; and, finally, that hot-wire ammeters are necessary in both the aerial and oscillation circuit to determine whether the set is actually transmitting high-frequency waves and whether these are smooth so that the conversation and music will be heard at the receiving end.