Reginald Aubrey  Fessenden

To the Editor of the SCIENTIFIC AMERICAN: 

    The first point in regard to which information is desired is this: 

    About November, 1906, my Brant Rock, Massachusetts, and Macrihamish, Scotland, wireless stations were in operation, and we were working mostly "G" tuner frequency 70,000 cycles per second, to avoid daylight absorption. 
    We shut down for about a month at this time to make some change in the sending apparatus of the Macrihamish end, but continued sending occasionally from Brant Rock, though most of the time at Brant Rock was spent, while waiting for Macrihamish to be completed, in installing and testing our new wireless telephone system between the station at Brant Rock, Massachusetts, and a station at Plymouth, Massachusetts, about twelve miles away. 
    Meantime the operators at Macrihamish were listening regularly every night to other stations, partly for the purpose of keeping in practice and obtaining data as to atmospheric absorption, etc., and partly so as to be sure to get any messages which might be sent from Brant Rock, as we were using wireless exclusively in order to save cable expenses. Practically all the listening was done on "G" tune as we had shortly previously made our very important discovery, later published in the Electrician, that while the absorption increased with increased wave length up to about 100,000 frequency, beyond that point the absorption fell off very rapidly as the frequency was decreased until at about 70,000 frequency the absorption was comparatively small. 
    Sometime, I think, in November, 1906, I received a registered letter marked Personal from one of the Macrihamish operators. In this letter he stated that he had been listening in on a certain date, which he specified, and at a certain hour, about four o'clock in the morning as I recollect it, and had noticed a remarkable phenomenon which showed that speech could be transmitted by speaking in proximity to the rotary spark gap (we were then using 10 kw. rotary spark gap, giving about 500 or 1,000 sparks per second). He stated that at the date and hour specified he had heard one of our Brant Rock engineers giving instructions to one of his assistants in regard to the running of the dynamo; that the speech had come in very clear and plain, and that he was able to identify the speaker as Mr. Stein (now, I believe, with the Bell Telephone Company); he wrote out in detail the words which he stated he had heard Mr. Stein speak to his assistant as he had written them down after hearing them; the whole amounting to five or six sentences totalling between fifty and one hundred words. 
    He stated that he had not reported this to me by wireless because other stations listening in might have got the report and he considered it too important to run any risk of premature disclosure. He also stated that he was sending it by special registered letter for the same reason. 
    My first thought was that the operator had made some mistake and that possibly some experimenters in England had also been working with my wireless telephone, since the patent disclosing the invention had been issued some years previously, and we had given a number of demonstrations of the telephoning operation. 
    However, I called in Mr. Stein and repeated to him the instructions which the Macrihamish operator had overheard Stein giving to his assistant, and asked Mr. Stein if he had given any such instructions to his assistant in the Brant Rock station. Mr. Stein stated at once that he had not given any such instructions to his assistant in the Brant Rock station and that the instructions so given did not relate to any of the apparatus in the Brant Rock station, but related to the motor generator set for driving the high frequency telephone arc at the Plymouth station. I asked Mr. Stein when he gave the instructions, and he said he did not know, but could tell by looking up the station log, which he did and reported that they were given on the night of a certain date, between certain hours on that night, those hours being the hours as shown by the station log between which tests were being made which would require such instructions being given. 
    The date and hours given by Mr. Stein without knowledge of the date and hours given by the Macrihamish operator, coincided exactly, after allowance had been made for the difference in time between Macrihamish and Brant Rock, with the date and hour given by the Macrihamish operator, and it became evident at once that what had happened was that the Macrihamish operator, listening on "G" tune which was the same frequency used for working telegraphically between the Brant Rock and Macrihamish stations and the frequency used for working telephonically between Brant Rock and Plymouth, had overheard Mr. Stein at the Brant Rock station giving instructions by wireless telephone to his assistant at the Plymouth wireless telephone station. 
    In this connection I would say that the Macrihamish operator's conjecture that speech transmission was due to the fact that Mr. Stein was standing near the rotating arc gap when giving his instructions, was formed without his knowing that we had just received our first high frequency generator which had been built in our Washington shops (I may say that this high frequency dynamo giving about ½ kw. at 70,000 cycles, a photograph of which appeared in the Electrical Review for February 15, 1907, was still in good condition last year after ten years' service though not so efficient electrically as the larger sized high frequency dynamos later so admirably designed by Mr. Alexanderson and built for us by the General Electric Company). 
    The Macrihamish operator's theory that speech might be transmitted wirelessly by speaking close up to an arc was aside from its ingenuity by no means unsound for I later made some experiments to test this point and found that under certain conditions and with the arc at a certain adjustment, speech could actually be so transmitted, though the articulation was not good enough for commercial work. 

    The reason why the operator did not get the talking every night will be seen from examining the curve showing variation of intensity of transatlantic messages for the month of January, 1906, published in the Electrical Review, May 11, 1906, and reproduced herewith. 
    From this curve it will be seen that during the month of January the average intensity of the messages was less than five time audibility, but that on five nights, i. e., January 9th, 10th, 11th, 29th and 30th, it was above 100 times audibility; on one night, January 10th, it was 225 times audibility, and on one night, January 30th, it was 500 times audibility, the signals on these latter two nights being so loud that they could be heard all over the receiving room with the head phones lying on the table. This curve of intensity of transatlantic wireless transmission was made with the 10 kw. telegraph set referred to above. Consequently since the 70,000 cycle alternator only gave ½ kw., the intensity of telegraphic signals received from it would only be 1/20 as strong, and consequently would only be heard on the five nights on which the intensity was more than 20 with the 10 kw. set. 
    In addition to this, however, telephonic transmission is not so efficient as telegraphic transmission, i. e., it takes more power to telephone wirelessly a given distance than it does to telegraph wirelessly. In my paper on Wireless Telegraphy, (American Institute, Electrical Engineers, June 29, 1908) I have given the ratio experimentally determined as 10:1, for good telephonic transmission. Assuming this ratio, we see that telephonic transmission could only be accomplished across the Atlantic on those two nights, January 10th and 30th, on which the transmission was more than 200 times audibility, and consequently it was only a few days during each of the winter months that the Macrihamish observer was able to overhear the telephonic transmission between Brant Rock and Plymouth. 
    After ascertaining these facts, I decided to give a demonstration of transatlantic wireless telephony at the earliest possible moment, and pushed forward the construction of the new 1½ kw. generator which was being designed for us by Mr. Alexanderson. 
    About a week or ten days later, I received a second letter from the Macrihamish operator, stating that he had heard the talking again, giving dates and times and record of the words said, and urging that I take up the matter at once. A program of transatlantic telephonic tests was drawn up, and arrangements were made to carry out a series of telephonic tests between Brant Rock and Macrihamish, when unfortunately owing to the carelessness of one of the contractors employed in shifting some of the supporting cables of the Macrihamish (as described in the Engineer, January 18th and 25th, 1907), it fell down on December 6th, 1906. 
    No publication was made at the time of the results of these two pioneer instances of transatlantic telephonic communication because prior to and at that time there had occurred a considerable number of instances where entirely false claims had been made in regard to transatlantic working, and some which the writer had had a hand in exposing; for example, the false claim that messages had been transmitted across the Atlantic to Newfoundland, and any statement made that telephonic transmission had been accomplished across the Atlantic would have been looked upon with incredulity especially in view of the fact that Macrihamish tower had fallen down, and hence no confirming demonstration could be given. 
    It was therefore decided to wait until the Macrihamish tower had been rebuilt, and then give a public demonstration before making any public reference to these facts mentioned above. 
    The Macrihamish tower was however, never rebuilt, and consequently the public demonstration was never given. 
    A history of wireless telegraphy and telephony such as the one which the writer has at present in preparation, would, however, be incomplete without reference to these facts, and as I have been so long disconnected with wireless telegraphy, and am not able to obtain the correspondence and records relating to this matter I should be very much obliged if any of the readers of the SCIENTIFIC AMERICAN who may have of the facts would please write me. 

1. What was the name of the Macrihamish operator who notified me of these two pioneer instances of transatlantic telephonic transmission? 
2. What were the dates and times at which they took place? 
3. Is my recollection correct that it was Mr. Stein whom the operator overheard giving instructions to his assistant? 
4. Who were the operators in Guantanamo, Panama, and Nebraska (or was it Michigan?), who wrote me about that time that they had overheard our telephonic work between Brant Rock and Plymouth, giving dates and times? 

1. In what publication or publications and on what date did the writer's first description of his system of telegraphing by pure sine waves without making or breaking the circuit, appear? The first test was made in 1892 at the standard Laboratory and later continued at Purdue and Pittsburgh Universities and in some place a full description has been published of the apparatus which description I have been unable to locate. 
2. In what publication and on what date did the writer's description of his resonance analyzer appear? This was a system of parallel tune circuits, tuned to different frequencies, used for analyzing complex periodic functions. It was built by Queen & Company for the writer about 1901, and the publication describes its application to the measurements of the frequencies of static disturbances at different hours of the day, and their relative intensities. Though it has since been superseded by the heterodyne analyzer, it is not unimportant historically. 
3. Who were the students at Purdue who in 1892-93 carried out the tests on the writer's hot wire anemometer and is any copy of this thesis still in existence?