The yacht Hirondelle's radiotelegraph transmitter used a Lepel "quenched" spark. Because the spark frequency was adjustable, it could produce varying notes, suitable for musical serenades.
New York Herald, September 11, 1913, page 5:

Prince  of  Monaco  Sees  City  After  Forty-Five  Years  and  Explains  Musical  Mystery  of  the  Sea
Prince Albert I of Monaco

Noted  Scientist  and  Sportsman  Arrives  in  Hudson  on  Board  the  Hirondelle.


Ruler  of  Principality  Will  Go West  for  the  Purpose  of  Shooting  a  Grizzly  Bear.

    Albert I., Prince of Monaco, sportsman and scientist of worldwide fame, arrived in the Hudson River yesterday morning on board the steam yacht Hirondelle, while melody from her wireless was wafted through the air.
    It was told in yesterday's HERALD how this vessel of unusual type had reached Quarantine on Tuesday night, her coming made known by the music which vibrated from the antennae high on her masts. The tune was caught by the operator at the wireless station of the HERALD Ship News Office at the Battery, and greeting was sent to the distinguished scientist. The voice of this sea swallow was due to a pianolike attachment to what is considered the most remarkable wireless equipment which ever has come to this port. The notes may be heard over sea and land for many a mile. Several incoming vessels, including the Grosser Kurfurst, of the North German Lloyd line, reported hearing siren strains as they neared the coast, and the mystery is now solved.
    The Hirondelle last night at half-past nine o'clock gave a wireless concert, having first asked the HERALD station to notify all vessels within range. There were popular selections, the "Marseillaise" and "America" upon the programme. The music was heard by operators at wireless stations for many miles and at the Brooklyn Navy Yard and by persons who were permitted to put on the telephone head pieces at the stations. The vessels within call thanked the Hirondelle for the entertainment.
    The Hirondelle, after leaving Monaco early in the summer, went to the Azores, then to Halifax, and after a sojourn of ten days there proceeded to sea again on August 24, to explore the ocean deeps beyond the Grand Banks. It had been the intention of the Prince to be in New York about the fifteenth of this month, so his aerial serenade was a surprise. The yacht is a floating laboratory of science, and it bears tons of apparatus and appliances used in the study of life near the bottom of the North Atlantic, to which her owner has given twenty-five years of study.

Hopes  to  Shoot  a  Grizzly  Bear.

    He will leave here to-morrow with his party for Wyoming, where he hopes to shoot a grizzly bear. After two weeks or so he will return to this city. If time permits, the Prince may see some of the American universities and scientific institutions, and may visit the national capital. The Hirondelle meanwhile will be taken back to her home port by Captain d'Arodess, and her owner will be a passenger on board one of the large ocean steamships bound for Europe.
    Truly a vessel of wonders is this craft, where science reigns. It is equipped with appliances which have been used in fathoming the riddles of nature. Much of the apparatus employed was invented by the owner, and there are workshops and a well equipped laboratory on board where his new ideas can be put in practice.
    All the electrical equipment represents the last word, but the wireless piano causes looks of astonishment to come upon the faces of operators ashore and afloat. The wireless system in use on the Hirondelle is the invention of Baron von Lepel and the patents are controlled by the Compagnie Generale Radiotelegraphique of Paris. It employs a continuous current with a high pressure of 1,500 volts, which charges the condensers without a transformer. It has a revolving sparker, a series of small wheels. The spark is only a tenth of an inch in length and is always [rest of sentence missing]. The whole apparatus is remarkably compact, for both the sending and receiving appliances easily are placed on one small table. The primary coil consists of one spiral and in the secondary coil are forty turns or spiral.
    With this system, which is called an impulsive one, it is possible to get high frequency oscillations. The vibrations are so many that often it is impossible for the ear to perceive them and the note to be heard. The inventor has put on the sparker another oscillatory circuit, and a variable condenser. He can thus lower the frequency of the system. The use of a variable condenser in the second circuit makes it possible to get different frequencies, which may be tuned to musical notes. The variations are made by striking a bank of ten keys, arranged in the form of a keyboard of a piano.
    The operator, Pierre Boutteville, sitting at the table, can let his fingers stray over them and by certain adjustments can get twenty variations. This is a stock of notes enough for a Paderewski. From the wireless piano of the Hirondelle have come "God Save the Queen," national anthems and even waltzes from such sprightly operas as "The Merry Widow."
    The Prince was highly amused when I told him of the sensation which the musical début of Mlle. Hirondelle had made in these latitudes.

Far  Ahead  of  Marconi  System.

    "It always causes astonishment," said he, "and we have been asked at sea if the music could possibly be made in this way. Yet it is all very simple. The harmony is produced as easily as playing on a piano. The system on board is really a remarkable one. Much better, in fact, than the Marconi, which is far behind the times and seems to be devoted to stopping progress. We are able to communicate fifteen hundred miles, and so, in crossing the Atlantic, are not likely to be out of touch with land for very long. There is one instance where we received messages from both sides of the Atlantic."
    The Prince received me in the saloon of the Hirondelle, where on all sides were panels painted with scenes of hunting and fishing in many climes, the records of many voyages. Erect of figure, with an air of abounding vitality, he is the typical yachtsman and sportsman. His beard, slightly touched with gray, is the only evidence of his sixty-five years. His eye is clear and kindly, his step light and elastic. He says he felt as strong as a man of thirty, and certainly looks it. Harpooning whales, shooting big game and wooing the sea in all kinds of weather have kept him lithe and strong.
    He is a teetotaler and does not smoke. The recipe which he has for keeping young is work and sport. He always is busy. The head of a principality, in which is glittering Monte Carlo, he is also a biologist and an oceanographer, whose reputation would have been as great in the world of science without his princely rank. He is the author of scores of books and brochures on his favorite study. In his laboratory on the Hirondelle his contributions to the literature of science make Dr. Eliot's five foot book shelf seem small indeed.
    "I like to make sport," said the Prince, "for it makes sport for others and adds zest to life. I have long wanted to shoot a grizzly. I will be content with just one."
    The Prince learned all the tactics of the art in Arctic seas and has slain the leviathan with his own hands. In the saloon are three paintings which show him in a small boat in the very centre of conflict.

Was  Here  Forty-five  Years  Ago.

    The Hirondelle was anchored near Ninety-eighth street not far from the old American wooden man of war, the Granite State. The Prince recalled that forty-five years ago he came to New York as an officer in the Spanish navy and had found it a very pleasant city.
    "And as I came up the Bay," he said, "I noticed that your city had indeed become much greater."
    Education greatly interests the Prince of Monaco and he has followed the intellectual progress of the United States in all its phases.
    "I greatly admire this country," said he, "and especially for what its young science is accomplishing. It is all so promising, and here there is such enthusiasm for progress. I see a young people, which, wanting general knowledge, is enlarging its ideas and cultivating great ideals. Here are great influences at work. Your scientific institutions are accomplishing much and I have noticed that important steps in this development are due to individual Americans, men of wealth who have given of their private fortunes to advance the cause of science. The Rockefeller Institute is an example of this. I have had the pleasure of corresponding with many American scientists and in the Smithsonian Institution I have an especial interest."

Essentially  a  Scientific  Craft

    The Prince, when I asked him more concerning the scientific work which had been accomplished recently on board the Hirondelle, took me to the laboratory.
    "This," he said, "is essentially a scientific vessel and afterward a yacht."
    The Hirondelle is a steel twin screw steam yacht, with an auxiliary brigantine rig. She carries unusually lofty masts, which seem to dwarf the single funnel. The yacht is 291 feet over all, 36 feet in beam and has a draught of 17 feet 8 inches. Her lines indicate that she is a very dry vessel indeed, with her high top gallant forecastle and the raised after deck. She has a clipper bow and her lines are trim and graceful. On the flag is the coat of arms of Monaco, with the Latin motto "Deo Juvante" (With God Aiding). Below decks there is every evidence of strength and careful workmanship. There are substantial bulkheads, with heavy doors. The crew, under command of Captain d'Arodes, of the French navy, consists of fifty men and the total number of persons on board is sixty-eight, including officers, scientists, photographers and artists. Not only has the Hirondelle every appliance which modern naval architecture has prescribed for a yacht, but it has special apparatus, which represents inventive talents of a high order. Among them is a machine for sounding. Invented by the Prince himself, by means of which the seas have been measured for a depth of 5,200 metres or about three miles. Here also are contrivances for bringing up water from great depths for analysis. There are nets with which the strange denizens of the uttermost depths are drawn to the surface. A complete outfit for whale hunting also was to be seen.

Migration  in  the  Ocean.

    The laboratory itself is light and commodious and filled with an array of bottles and jars. The creatures of the depths are studied here and preserved for further examination at the museum which the Prince established at Monaco.
    One of the significant facts which the explorations of the Hirondelle expedition has revealed is that there is a constant vertical migration in the ocean, and that forms of life which scientists have believed could not live near the ocean floor are constantly coming up near the surface. They travel very slowly in order to get accustomed to the variations of pressure. Those which are brought up by the nets from the depths usually collapse and die because of the too sudden change.
    There are many new forms of life to be seen in the laboratory and to be later pictured and described. The laboratory is under the direction of Dr. J. Richard, who is the director of the museum at Monaco. Dr. Albert Ranc, of the Sorbonne, is also on board. The artist who depicts the changing colors of the fish as soon as they are drawn up is Louis Tenayre, who in his capacity of official painter, also has decorated the salon panels. The Prince spends much of his time in the laboratory studying the phosphorescent fish and the other strange forms which come under his observation and that of his scientific companions.

Fish  Bite  Miles  Below  Surface.

    Fish bite, too, at a depth of several miles, as actual demonstration by long distance angling shows. Always a spectator of the fishing is Joe, the fox terrier mascot of the Hirondelle, who joined as a "ratter" ten years ago. Joe's principal diet is mackerel and he is especially fond of the red shrimp which come from below the three mile limit counting downwards.
    The Prince went ashore in the afternoon and, after taking a constitutional down Broadway, decided to try a street car. He offered as fare a ten franc gold piece which the conductor rejected with the gruff observation:--"Say, we don't take any Guinea money here." The Prince asked his secretary for change and he had none. A reporter who possessed three nickels, which were more readily convertible coins of the realm, paid the fares. The Prince went to a sporting goods house in West Thirty-sixth street, where he purchased additional supplies for his big game expedition.
Wireless Telegraphy and Telephony Simply Explained, A. P. Morgan, 1912, page 96:
New York Herald radiotelegraph station (WHB, originally OHX)
New York Herald radiotelegraph station (WHB, originally OHX)