Technical World Magazine, May, 1910, pages 257-264:
W I R E L E S S T E L E P H O N E W I Z A R D R Y
B y
W I N S T O N R. F A R W E L L
WIRELESS telephony is being developed at a rate that makes the plain citizen who aspires to be informed concerning the progress of the world hustle to keep up with the state of the art. Already A. Frederick Collins, the pioneer worker along this line has developed three distinct systems of wireless telephones, each adapted to a certain sphere of usefulness, each practicable and reliable, and goodness knows how many more he may turn out before the ink on these pages is dry.
The things that can be done with one or the other of these three systems would stagger the credulity of any but a people who by long familiarity with scientific marvels have become hardened thereto. It is now possible to talk without the use of wires with persons in distant parts of a building or in adjacent buildings regardless of the number and thickness of walls and floors intervening. One may take a wireless telephone on an automobile, a motor boat, a yacht, an airship or a submarine, into a caisson, a tunnel or a mine and be able to converse with others at any given point or points on the surface as freely and as plainly as one can now talk over a local telephone with nearby points.
It is even possible to combine the ordinary telephone with the wireless. Thus a telephone subscriber in Creston, Iowa, for instance, who wanted to talk with some one on board the Deutschland in mid-Atlantic need not be deterred by the fact that there was no wireless station at Creston. All he would have to do would be to call up Chicago on the long distance wire. Chicago would give the connection with the New York wire and the New York office would connect with the wireless station. The wireless operator, after calling the Deutschland by wireless, would connect the long distance wire from Creston with the wireless transmitter and the voice that had already traveled fourteen hundred miles overland by wire would project itself through the ether to the listening ear on shipboard on the lonely Atlantic.
In fact there seems to be few, if any, situations to which the wireless telephone is not adapted. In addition to the familiar daily use of the telephone the wireless will open up many new fields that cannot be occupied with pole and wire. Harbor craft, tugs and ferryboats can get into instantaneous communication with offices on shore and receive orders or changes in instructions while out on the water. When vessels are equipped with wireless telephones the pilot will be able to call up the pilot on another craft that persists in getting in his way and tell the offender privately what he thinks of him, his conduct and his ancestors instead of bawling his opinions out at an open window at the risk of having his license revoked by some horrified steamboat inspector. And when some badly rattled navigator betrays symptoms of intending to try to pass on both sides of another vessel at the same time the wireless telephone may be the means of saving both lives and property. The wireless telephone is the first notable improvement in marine signalling since the introduction of the steam whistle. Fogs, darkness and storms have no effect on the wireless telephone. And out in the country where subscribers are too few to warrant the installation of a wire system the wireless 'phone will afford a cheap and certain means of communication.
In the ordinary, every-day business of life the wireless 'phone has advantages over the more familiar system. When a message is transmitted over a wire a certain amount of electricity is required to charge the wire before any words can be spoken. Under these conditions, however clear and distinct the words may be uttered, the longer the line the greater will be the distortion of the undulatory current until the words become so inarticulate they cannot be understood. But with the wireless, if the waves representing the voice are pure when they are emitted through the aerial wire they will carry clear and distinct the greatest distance the instrument is capable of propelling them. This is because the message is sent through ether, a medium which does not require to be electrically charged and which consequently does not distort the wave forms representing the voice. It would seem, therefore, that the wireless is the natural way for the transmission of messages while the wire line is the artificial way.
Another advantage the wireless 'phone has over the ordinary system is in calling. Instead of asking an operator at central to get a certain number for him the lucky possessor of a wireless 'phone can ring up his man instantaneously and talk directly with him. By means of disks with numbers on the edge, something like those used for the combinations of safes, the caller can tune his 'phone with a certain number in much the same way that the subscribers to the automatic telephone system in Chicago and elsewhere call a number through electrical selectors. By turning the disk to a certain number the particular 'phone wanted will respond, and no other.
Finally, the wireless is cheaper to install and, maintain, for there is no costly copper wire and cedar poles to buy and set up and replace every time there is a little storm.
Now, do not get excited and conjure up visions of the Western Union Telegraph and Bell Telephone Company being driven into bankruptcy by the triumphal competition of the wireless 'phone while the stockholders therein haunt the bread line and the municipal lodging house, for nothing of the kind likely to happen. At least, that is what Collins says. Being deliberate in speech Mr. Collins has time to edit his remarks as he goes along. The result is an estimate of his numerous inventions that has the ring of sound common sense. Here it is.
"It is not at all likely that the wireless telephone will take the place of the ordinary telephone--at least, in my lifetime, and I am only forty-one and a good life-insurance risk. You may remember the more enthusiastic prophets predicted when the Bell telephone was first brought out that it would put the telegraph companies out of business. Instead of that the demands upon the telegraph companies have enormously increased, while at the same time the telephone system has grown to vast proportions. Both combined have failed to prevent the volume of first class mail from doubling every few years.
"From these premises I draw the comforting conclusion that the world is progressing so rapidly that it needs all the means of communication that can possibly be provided. That is what has encouraged me to devote ten years of my life to the development of the wireless telephone. I do not expect even to affect the telephone system, but I feel confident of helping out by doing many things the ordinary telephone cannot do, for you see I can telephone without wires where it is impossible to telephone with wires."
One of the places where the wireless telephone will be particularly valuable will be in mines. Now, any one who wants telephone connection with the underground workings of a mine has only to string a wire down the shaft. But if there should be a fire or an explosion or if anything else should go wrong the frail wire would be cut off at the very time when the need of it was greatest. But portable conductivity wireless sets could be carried around anywhere by gangs of workmen. All they would need to do would be to drive an iron peg into the earth or rocks to make a ground contact and they would be in communication with the surface regardless of cave-ins, explosions, gas, flames or any other contingency. Many a life could be saved in mine disasters if the survivors only could communicate with the rescuing parties to direct their search. This conductivity wireless system has been tested up to a distance of three and a half miles and worked perfectly. It has been installed in a number of Western mines.
This ability to talk through miles of rock and earth rather staggers the credulity even of the layman who has brought himself to believe in the wireless telegraph. It may be all right to send an electric impulse through the unobstructed air, but rocks and earth are so much more substantial that it would seem to be quite a different matter to pass any sort of impulse through them. But the explanation is very simple.
Morse used the earth for the return circuit in the first form of electric communication given to the world. In other words, it has been known since the first practical application of electricity that the earth was a good electric conductor. In fact there are electric currents in the earth independent of any sent there by man. All Collins had to do, therefore, was to find a way to utilize the conductor already at hand. The task was not easy, but the application of the discovery is.
Ground plates on the same general principle as those used in the ordinary telegraph are buried in moist earth at the surface station. A current, either direct or alternating, is sent through these base plates into the earth where it spreads in elliptic lines of force, like magnetic lines between the poles of a magnet, until they reach the receiving plate down in the mine at any depth or distance.
Simpler yet is the inductivity method, which is limited to a few hundred feet, but which makes an ideal means of communication in office, factory, dwelling or warehouse. The apparatus consists, in addition to the usual transmitter and receiver, of a large primary coil of wire wrapped in insulating cloth until it looks like one of those hoops that children play with. At the receiving 'phone is a secondary coil of similar appearance. On speaking into the transmitter with a battery in series with the primary coil, an undulatory current rotating through the wire will set up a magnetic flow in concentric rings which keep spreading until they come in contact with the secondary coil. A more elaborate development of the inductivity apparatus is contained in a portable wooden case of about the size of an ordinary dress suit case. Within its distance limits the inductivity wireless, therefore, is about as convenient a means of communication as can be imagined.
Inventor Collins, however, is building his largest hopes on the third, or electric wave system. Whereas in the conductivity system energy decreases as the cube of the distance, in the electric wave system the energy decreases only as the square of the distance.
It should be borne in mind that wireless telephony is quite a different thing from wireless telegraphy; for in the latter an electric impulse of any character may be utilized as a signal, whereas in telephoning an alternating current having the same phase, amplitude and frequency at both sending and receiving stations is required. Thus electric waves produced by the disruptive discharge, which decrease very rapidly, dying out entirely in the very small fraction of a second, can not take the place of the long, smooth sine wave currents used in telephoning.
Beginning in 1899 Mr. Collins was able to telephone by the electric wave system no more than two hundred feet. A year later he had increased the distance to a mile; and by 1902 he was able to talk a distance of three miles. After a few more years he was able to talk from Newark to Philadelphia, a distance of eighty-one miles. Now he has reached a point where he expects to talk from New York to Chicago. The day may come when it will be possible to talk across the Atlantic, something more than twice the distance between these two cities.
One of the newest features developed, for which patents have just been issued, is a process by which the difficulty of tuning is overcome. By means of the new apparatus one circuit can be tuned with another automatically, thus rendering it possible for any telephone to call any other without any risk of interference by an outside party.
This particular type of wireless telephone was one of the features of the Alaska-Yukon-Pacific Exposition at Seattle last summer; where it won the gold medal, the highest award. Added interest is lent by the fact that plans are under consideration to equip all vessels in the United States navy with wireless telephones.
So far as outward appearances go the Collins electric wave wireless telephone resembles the ordinary telephone only in having the usual transmitter and receiver. The rest is strange.
One of the most weirdly spectacular features of telharmonic music produced by that wonderful electrical musical instrument invented by a Massachusetts doctor a few years ago, was the possibility of delivering music and light at the same time through the same arc lamp. The Collins wireless telephone is suggestive of telharmonic music in the fact that you talk through an arc light. This arc lamp, however, is fundamentally different from the ordinary kind as seen on the street. The latter may do to deliver music in plain air at short range; but when it comes to transmitting the human voice, which is rarely musical, long distances through ether, which is fifteen trillion times lighter than air, so light in fact that a ball of it the size of the earth weighs only two hundred and fifty pounds, at the rate of one hundred and sixty-eight thousand miles a second, something very special in the line of arc lamps is required.
In the Collins "revolving oscillation arc lamp" the carbons are disks instead of pencils, and they revolve at very high speeds in opposite directions. This is to prevent them from burning unevenly as ordinary carbons do, which would throw the circuits out of resonance and make talking impossible, and also to produce a longer arc than is possible with ordinary carbons. The carbons are enclosed in a casing which is supported between the poles of an electro-magnet. Through the ends of the poles of this magnet and at right angles to them are polar projections of soft iron threaded and screwed through the extremities of the magnet at right angles to the arc, thus permitting the magnetic field to be varied within wide limits. The coils of the magnet are used as a portion of the primary circuit of the transmitter, serving the purpose of choke coils to prevent the oscillations from backing up into the high tension direct current generator. The current is also very different from that used in the ordinary arc light, for it is received as a direct current of five hundred volts by a direct connected motor generator set and stepped up to five thousand volts before it is used to energize the lamp.
Other apparatus consists of an inductance transformer by means of which the telephone transmitter is tuned. In outward appearance it is a cylinder about two feet long, consisting of a solid core wound with wire surrounded by a spiral ring. On the base is a little track on which a carriage runs on which are three small grooved pulleys that are held in contact with the spiral ring. When the ring is revolved it causes the carriage to travel back and forth, thus increasing or decreasing the inductance, in order to get the closed oscillating circuit in resonance with the open radiating circuit.
The tuning auto transformer used in the aerial wire circuit is another large wire-wound core with a screw mounted on top with a wheel at the end. By turning the wheel the contact spring is made to travel back and forth. The variable condenser consists of a number of semi-circular fixed plates of metal insulated in a cylinder filled with oil with a series of movable plates meshed with, but insulated by the oil from, the stationary set. A handle attached to the rod permits any variation of capacity within the limits of the condenser.
The receptor includes a thermo-electric detector, the principal features of which are two exceedingly fine wires of and forming a couple. Under the junction of these wires is placed a resistance wire which is heated by the currents surging in the aerial system. This detector is exceedingly sensitive. As the electricians put it, it is sensitive to the five-thousandth of an erg, which means in plain English that it is sensitive enough to pick up all the varying inflections of the human voice.
The highest degree of tuning is obtained by a thermo-galvanometer, which consists of a single loop of silver wire suspended between the poles of a permanent magnet. The lower ends of the loop are connected with a bismuth-antimony thermo-couple which is heated by a fine filament of high specific resistance, through which the oscillating current passes. One end of the heater is connected with the frame of the instrument. The heat generated falls on the thermo-junction and the resulting electro-motive force applied to the ends of the silver loop causes it to turn in the magnet field.
