An earlier version of this article, Wireless Interference, appeared in the April, 1909 Electrician and Mechanic.
The Outlook, January 15, 1910, pages 131-135:

PRACTICALLY every passenger-carrying steam vessel of any size in American waters, and many freight boats and even tugs, are equipped with wireless telegraphy. Every ship in the American navy, including colliers and revenue cutters, carries wireless operators, and for the purpose of keeping in touch with naval vessels at sea the Navy Department has constructed a line of shore stations reaching from Maine to Alaska.
    In the last two years another wireless system has been gradually developing, a system that has far outstripped all others in size and popularity. It is estimated that throughout the United States over four thousand amateur wireless telegraph stations are in active operation. Hundreds of school-boys in every part of the country have taken to this most popular scientific fad, and, by copying the instruments used at the regular stations and constructing apparatus out of all kinds of electrical junk, have built wireless equipments that in some cases approach the naval stations in efficiency. These amateur operators have learned the commercial and naval telegraph codes and are able to receive the Government wireless despatches as accurately and promptly as the naval operators for whom they are intended. Official despatches sent out to naval vessels at sea from the shore stations of the navy become the common property of any amateur who takes the trouble to copy them on paper. Moreover, in some localities, amateur stations have interfered with the reception of Government messages, and have been responsible for long delays in the forwarding of official business. The efficiency of a number of the coastal stations of the navy has been cut in half because of the presence of dozens of small amateur stations.
    Boston is the headquarters of some five hundred amateur operators, a number of whom can put the Charlestown Navy-Yard completely out of commission as regards the receiving of messages. A single amateur station of low power can absolutely prevent the reception of wireless messages at this as well as at other naval stations. New York, Washington, and Baltimore have several hundred amateurs each, and a similar line of amateur stations extends along the Pacific coast from California to Alaska. In the interior the amateur forces reach into the thousands. A town of nine hundred inhabitants in upper New York State is the proud possessor of twenty-eight amateur wireless stations. Three electrical publications cater almost exclusively to these operators, and several manufacturers of electrical apparatus advertise wireless instruments for amateurs guaranteed to work up to several hundred miles.
    The result of this interest in wireless is the creation of the problem of the so-called amateur interference, a problem which, especially for the Navy Department, has reached threatening proportions.
    In a remarkably short interval of time wireless telegraphy has come to exercise an important function in the marine service. By means of the shore stations of the commercial companies, press despatches, storm warnings, weather reports, etc., are regularly transmitted to ships at sea. Captains of vessels keep in touch with each other and with the home office, and reports of wrecks, derelicts, threatening weather, or orders from the company's headquarters are sent over the land telegraph lines to and from the most convenient coastal stations. Every ship operator sends in regular reports, giving the approximate position of the vessel at a certain time, together with any other important information at hand. Thus the position and distance of a ship at sea may be determined at short notice, and, in case of emergency, every vessel within a certain radius may be ordered to hurry to the assistance of the ship in distress.
    In addition to the naval stations on board ship, a large number of naval shore stations are in operation at the principal navy-yards, forts, and lighthouses on both sides of the continent. These stations are supposed to keep in touch with naval vessels in the vicinity, to send out weather reports, receive official messages from all ships, handle the routine business of the department, and to be ready for any cases of emergency. The naval wireless system is thus a distinct part of the National defense, and no efforts should be spared to keep the equipment thoroughly modern and efficient.
    Every consideration, therefore, points to the conclusion that any needless interference with, or interruption of, wireless communication is directed against public safety and National organization.
    During the anxious hours that followed the collision between the Republic and the Florida, last January, the naval stations at Portsmouth, Charlestown, and Newport were often incapacitated through the working of amateur stations. Later, when the revenue cutters were standing by the Republic, communication with the land was at times entirely cut off for the same reason. Again and again the naval operators explained the situation and requested the amateurs not to use their instruments. Regardless of the warning, the interference continued, a number of the amateurs carrying on private conversations for hours.
    The sinking of the steamship Horatio Hall was attended by similar circumstances. No sooner had the emergency call been sent out from that vessel than dozens of amateur operators started up their apparatus. Requests from the naval stations were treated with indifference, some of the amateurs even arguing with the navy men over the ownership of the ether. That the thoughtless and even malicious interference of the amateurs did not have serious results was a fortunate accident.
    In order to appreciate fully the amateur question, it will be necessary to get a clear idea of the scientific meaning of the term "interference." Wireless messages are radiated through space in the form of electric waves or vibrations in the ether. Each dot and dash, representing a character in the telegraph code, is made up of thousands of electromagnetic waves that originate at the transmitting apparatus and fly off in every direction with the velocity of light, or 186,000 miles per second. The sending station contains instruments for the artificial production of these waves, while the receiving station must have apparatus sensitive enough to detect the presence of the waves, and to convert the energy received into intelligible signals. The familiar analogy of the motion of a wave in water may serve to illustrate the propagation of a vibratory disturbance in the ether. When a stone is thrown into the water, a series of ripples gradually spread outward in the form of circles. As the ripples leave the center of the original disturbance farther and farther behind, their strength diminishes until finally they fade away completely. It is clear that a chip of wood placed close to the center of the circle will be more violently agitated than a similar chip placed at a greater distance where the waves are correspondingly weaker.
    In much the same way, the electro-magnetic waves spread out in all directions from the aerial of a wireless telegraph station, gradually becoming weaker as the distance increases. If the chips of wood are now replaced by wireless receiving stations, it may be seen that the receiving instruments nearer the transmitting station will be more strongly affected by the electric waves than those situated at a greater distance. Thus a wireless message is received at all stations within the circumference of a circle that depends upon the strength of the sending apparatus and the sensitiveness of the receiving instruments, and the nearer the station the clearer will be the signal.
    Suppose, now, a coastal station is receiving a wireless message from a ship at sea, perhaps one hundred miles distant. Because of the distance the signals must travel, the dots and dashes are rather faint. Suddenly an amateur station within a few miles of the coastal station begins to transmit a message. Although the power of the amateur station may be small compared with that of the ship, it is much nearer to the coastal station, and its signals at that station will sound considerably louder than the signals from the distant ship. In other words, two separate series of waves reach the shore station together, and those produced by the amateur station, being the stronger, drown out the incoming signals from the sea. The shore operator finds it impossible to receive distant messages while the amateur station is working. Roughly speaking, this is what is meant by "amateur interference."
    It may now be readily understood why many of the naval stations are completely at the mercy of the neighboring amateurs. From early in the afternoon until late at night the amateur operators take possession of the ether, experimenting and testing with their apparatus, calling up their friends, carrying on long conversations on every conceivable topic, and occasionally varying the monotony by sounding the call letters of the nearest naval operator and inquiring about his health. This last seldom fails to call forth the wrath of the navy representative, and the heated wireless conversation that often follows is eagerly listened to by the rest of the amateurs, who sometimes join in the discussion. A Boston amateur, when recently told by a naval operator to "butt out," made the following classic remark: "Say, you navy people think you own the ether. Who ever heard of the navy, anyway? Beat it, you, beat it."
    An interesting record of amateur gossip as it is carried on over the ether has been compiled by one of the naval operators. The following selection is typical of the aerial chat that goes on for hours:
"How do you get me to-day? I am using my new transformer and my helix is hitched up different. How are your batteries holding out? Say, old man, I get you fine as silk. You have the navy skun a mile. My aerial came down last night, but I fixed it up again. Did you go to that show last night you spoke about? I have been too busy to go to town this week. Have you got any number thirty-two copper wire? Thought you would drop over last week. Say, old man, I met your lady friend yesterday. Ha, ha! Quit your kidding. Say, do you know the fellow who is putting up a new station out your way? I think he is a ham. Will call you up in ten minutes. Say, old man, must go to supper now, but will be on the rest of the night. O.K., O.K., will see you later."
    During this time the naval stations are cut off from communication except for short distances. At times, when important messages are expected, the amateurs are told to "break," and a few stop their instruments until the official despatches are received. Others continue, regardless of the warning, and hold up all departmental business in the vicinity unless the naval operator is able to copy a few words of the message between breaks in the amateur conversation. This results in long delays, which in a case of emergency might have serious consequences. It has been said that during certain hours of the day and night when the amateurs are out in full force a dozen ships might send out the emergency call without being heard at the shore stations. Only a very few of the amateurs have apparatus powerful enough to cause interference any great distance off the coast, and the trouble is therefore confined mainly to the coastal stations. Except when close to land, or when entering port, the ship operators experience little or no difficulty from this cause. The owners of high-power private stations capable of long-distance work have heretofore used their apparatus for scientific purposes only, and have been careful to avoid interfering with the regular operation of the naval and commercial stations. But in recent months a number of high-power stations have been erected by less responsible amateurs, and a single station of this description with a sending radius of a hundred miles or more can seriously reduce the efficiency of ship as well as of shore stations.
    Amateur interference can be eliminated only by one or both of two means: either the building of amateur stations must be prohibited or at least regulated by law, or the Navy Department and the commercial companies must adopt improved apparatus designed to prevent certain forms of interference, and so regulate the operation of their stations as to be immune from the accidental or malicious interfering of amateur operators. Although at first glance the former method would appear the simpler and more effective remedy, a careful consideration of the entire question of interference leads at once to the conclusion that, unless accompanied by scientific measures, legal action cannot bring about a satisfactory and efficient adjustment of the situation. The fundamental issue lies deeper than the amateur operator, and is plainly a matter for scientific as well as for legal solution. It is obvious that the agitation of the various wireless interests for the suppression of the amateur is only the first sign of a movement that must eventually result in a universal adjustment of the relations between the rival wireless telegraph companies and the naval systems, an adjustment that will require the services of both the scientist and the lawyer. Because of its nature, the ether, as a medium of international communication, will require safeguards in the form of wise restrictions and regulations, much as a city thoroughfare or other institution involving public safety and convenience demands efficient organization for the public good.
    Up to recent times the naval and commercial wireless stations have not been seriously inconvenienced by mutual interference. Although in many cases several stations are located in the same vicinity, and each would, under present means and methods of operation, interfere with the others unless care were taken to avoid conflict, but little trouble of this nature has been experienced. Each operator respects the rights of his neighbor and is careful not to "butt in" when messages are received. Thus in New York City, probably the busiest wireless spot in the world, a dozen naval and commercial stations have worked side by side with comparatively slight friction. But it should be noted that these harmonious conditions are the result of experience that has proven such co-operation absolutely necessary under present operating methods. For any programme that compels five stations to suspend all business while the sixth is working is obviously a waste that seriously reduces the efficiency of all stations involved. The construction of new coastal stations and the increasing number of ship outfits have brought matters to a point that demonstrates the total inability of means now in use to relieve interference difficulties without a systematic revision. It would thus seem that, leaving the amateur out of consideration, the naval and commercial interests are already involved in serious troubles due to interference.
    The first few years of wireless development in the commercial field witnessed the growth of a number of large companies, each working in its chosen territory with comparatively little competition. Under these circumstances wireless interference, except for a few specific cases, was not a cause for great complaint. More recently the rapid spreading and overlapping of the different commercial systems, the growth of the naval systems, the building of long-distance stations, and the consequent increase in the number of messages transmitted, have brought about what might be termed a congestion of aerial traffic. In 1906 the governments of the world, recognizing the need for a systematic regulation of wireless service, called together at Berlin the International Wireless Telegraph Conference. The plan finally drawn up by that body was signed by the representatives of twenty-seven countries, including the United States. Later, however, Congress refused to ratify the convention, the adoption of which would have given the Government control over all wireless systems in this country. Without discussing the effectiveness or ineffectiveness of the instrument as a whole, it is enough to note that in failing to indorse the Berlin Convention the Government gave up an opportunity to settle once and for all the case of the amateur operator. At present the Navy Department has no authority to deal with the amateur situation. Just how such authority is to be obtained is an interesting question, more especially in view of the fact that, in the general opinion of experts, at least eighty per cent of all wireless interference now experienced could be eliminated by the use of improved apparatus, together with the adoption of a special system of wave-lengths for the different wireless systems.
    Every wireless telegraph station may be constructed in such a manner as to send out electro-magnetic waves of a given length or period. In order to respond to these waves, the instruments at the receiving station must be adjusted to correspond to the wave-length, or period of oscillation of the transmitting apparatus. The adjustment of the receiving instruments to the incoming wave is called "tuning." If the wave-length of a station is fixed at, say, four hundred meters, messages from this station can be received at a distant station only in case the receiving instruments are tuned to approximately four hundred meters. With the latest improved apparatus for selective tuning, the wave must closely approach the tune of the instrument to be detected, and of a number of conflicting waves of slightly different lengths, any one may be received and the rest excluded. On the other hand, two or more waves of the same or nearly the same length cannot be separated and tuned out as desired, and will interfere one with the other. Without going into technical details, it should be seen that, even with the most selective apparatus, a number of wireless stations of about the same wave-length in the immediate vicinity must of necessity cause interference when more than one station is in operation at a time. Also, that the more selective the receiving instruments are, the greater is the number of stations that may work without mutual interference. The fact that practically all government, commercial, and amateur wireless stations are built for the same or approximately the same wave-length, and that not one in twenty is equipped with selective instruments, at once accounts for the greater part of interference difficulties, and also suggests two obvious remedies--the use of improved apparatus and of a system of varied wave-lengths.
    Suppose, for example, that the naval stations increase the length of their official wave to eight hundred meters and that the commercial companies adopt a series of wave-lengths varying by perhaps ten or twenty per cent. The use of selective instruments would then permit the simultaneous operation of the different groups of stations. Thus the naval stations might transmit their official despatches regardless of the operation of the hundreds of commercial establishments, or of the thousands of amateurs, who of course could be allowed to play with a non-interfering wave of limited range. By improved apparatus is meant both sending and receiving instruments, the former capable of sending out waves which for reception require the close adjustment of the latter. Such apparatus has long been known to the laboratory, and is the property of no one scientist or manufacturer. A number of new stations are employing this method with entire success, and it is obvious that all stations that suffer from interference must finally be protected by a means advocated by experts as offering the only permanent solution now available for the problem of interference.
    Objection has been made that a system of special wave-lengths would hinder communication between stations in cases of emergency. This difficulty may readily be avoided by the use of a standard wave for calling purposes in connection with the regular wave of the particular station. An operator wishing to communicate with any given station may sound the call signal of the station by means of the standard or universal wave. The receiving instruments of stations awaiting a call would be tuned to the universal wave, and when the desired station responds and communication is thus established, both operators, by a simple adjustment, may change over to the special wave and proceed with their business undisturbed. As the continued growth of wireless systems will doubtless further complicate the conditions of interference, it may be necessary to arrange for a more elaborate system of wave-lengths than here suggested. At present, however, the plan as outlined will easily meet the needs of the occasion.
    Clearly, therefore, the cure for wireless interference does not hinge alone on the extermination of the amateur operator. That the naval and commercial systems are suffering severely from amateur interference is an undeniable fact. Equally is it true that the amateur must be checked to some extent through legal procedure. He is, however, by no means the most important factor in the interference situation. Although his carelessness and ignorance have often been a source of just complaint, and his presence under present conditions inevitably adds much to the increasing difficulties of efficient wireless operation, there seems little necessity for the militia or a special session of Congress to dispose of his case. A slight amount of regulation will easily suffice to prevent the abuse by the irresponsible school-boy of his latest scientific toy. What is a more important need by far is the intelligent co-operation of the several wireless interests for the purpose of utilizing the latest products of the laboratory in a systematic effort to eliminate defects in methods of operation due, in part, to the rapid and unstandardized development of the science.