1880 __ Topophone
‣ Comment : “The aim of the topophone, which was invented and patented by Professor A. M. Mayer, last winter, is to enable the user to determine quickly and surely the exact direction and position of any source of sound. Our figure shows a portable style of the instrument; for use on ship-board it would probably form one of the fixtures of the pilot-house or the “bridge,” or both. In most cases arising in sailing through fogs, it would be enough for the captain or pilot to be sure of the exact direction of a fog horn, whistling buoy, or steam whistle; and for this a single aural observation suffices. Every one has twirled a tuning fork before the ear, and listened to the alternate swelling and sinking of the sound, as the sound waves from one tine re-enforce or counteract those from the other tine. The topophone is based upon the same fact, namely, the power of any sound to augment or destroy another of the same pitch, when ranged so that the sound waves of each act in unison with or in opposition to those of the other. Briefly described, the topophone consists of two resonators (or any other sound receivers) attached to a connecting bar or shoulder rest. The sound receivers are joined by flexible tubes, which unite for part of their length, and from which ear tubes proceed. One tube, it will be observed, carries a telescopic device by which its length can be varied. When the two resonators face the direction whence a sound comes, so as to receive simultaneously the same sonorous impulse, and are joined by tubes of equal length, the sound waves received from them will necessarily re-enforce each other and the sound will be augmented. If, on the contrary, the resonators being in the same position as regards the source of sound, the resonator tubes differ in length by half the wave length of the sound, the impulse from the one neutralizes that from the other, and the sound is obliterated. Accordingly, in determining the direction of the source of any sound with this instrument, the observer, guided by the varying intensity of the sound transmitted by the resonators, turns until their openings touch the same sound waves simultaneously, which position he recognizes either by the great augmentation of the sound (when the tube lengths are equal), or by the cessation of the sound, when the tubes vary so that the interference of the sound waves is perfect. In either case the determination of the direction of the source of the sound is almost instantaneous, and the two methods may be successively employed as checks upon each other's report. It is obvious that with such a help the pilot in a fog need never be long in doubt as to the direction of a warning signal; and if need be he can without much delay, by successive observations and a little calculation, determine, approximately at least, the distance of the sounding body.”. (in the July 3, 1880 issue of Scientific American, A WEEKLY JOURNAL OF PRACTICAL INFORMATION, ART, SCIENCE, MECHANICS, CHEMISTRY, AND MANUFACTURES. NEW YORK, July 3, 1880. Vol. XLIII.) — No. 1. [NEW SERIES.]). — From 1871 until his death in 1897, Alfred Mayer was a Professor of Physics at the Stevens Institute of Technology in Hoboken, New Jersey. His major papers include “The Determination of the Law Connecting the Pitch of a Sound with the Duration of Its Residual Sensation,” “On the Effects of Magnetization in Changing the Dimensions of Iron and Steel Bars,” “Experiments with Floating Magnets,” and “On Measures of Absolute Radiation.” (Michael Leong). — "Experimental Researches in the Determination of the Forms of Acoustic Wave-Surfaces, Leading to the Invention of the Topophone, an Instrument to Determine the Direction of a Source of Sound." by A.M. Mayer, In Jour. Otology, October, 1879. (cited in “A HISTORY OF THE STEVENS INSTITUTE OF TECHNOLOGY AND BIOGRAPHIES OF THE TRUSTEES, FACULTY, AND ALUMNI AND A RECORD OF THE ACHIEVEMENTS OF THE STEVENS FAMILY OF ENGINEERS”, edited by FRANKLIN DE RONDE FURMAN, Hoboken NJ : STEVENS INSTITUTE OF) — 15 June 1901 - Lieutenant Colonel D.P. Heap has devised an instrument, the Topophone, to assis sailors in fog. Several others have tried to develop a devce for locating a vessel and dertemining their course in fog and to-date no one has succeeded. Professor Elisha Gray developed a method of ringing bells underwater and Hamilton Foster blew a different whistle for every direction the foghorn is pointed. Due to the expensive cost of these, none were practical. Heap's Topophone was described in the "Scientific America" as "it consists of two acoustic receivers or trumpets, pointing in opposite directions and supported on a vertical shaft. From the lower ends of the trumpets extend rubber tubes, connected with the ears by specially constructed ear pieces. The observer holds the shaft so that the instrument is above his head, if a sound is heard in either ear - the right ear for example ) it shows at once hat the sound must be somewhere on his right hand side. If he then turns to the right until the sound is heard in his left ear, it shows that he has passed the direction of the sound. If he then oscillates the trumpets so that the sound is heard alternatively in each ear, the sound will be in a direction inside the angle of oscillation; this angle generally is about one point of the compass. The whole operation takes a few seconds.". (From the Bangor Daily Commercial, 1901; reprint in the Maine Coastal News, May 2009, p. 25)
‣ French comment : Le topophone imaginé par M. A.-M. Mayer est un instrument destiné à indiquer la direction des sons, et il peut être employé en mer pour indiquer la direction des signaux en temps de brouillard. (In "La Lumière Électrique) — Journal Universel d'Électricité", 1e série, vol. 4, n°27-52, 1881, Paris : Union des syndicats de l'électricité, 3ième Année, Mercredi 3 août 1881, No. 36, p. 158). — On sait combien la faculté auditive devient défectueuse quand elle n'est pas aidée par la vision. Qu'un navire soit plongé dans le brouillard, il lui sera fort difficile de percevoir exactement le point de départ d'un signal venant d'un autre navire qui marche à sa rencontre. C'est pour remédier à ce défaut de l'audition qu'un ingénieur du service des phares de Etats-Unis, M. Heap, a imaginé un appareil très sensible, le topophone (de topos, lieu, et phôné, voix) permettant de se rendre compte du lieu d'où part le signal d'avertissement. L'appareil est fait de deux récepteurs acoustiques dont les pavillons sont dirigés en sens opposé, et dont les embouchures sont élevées aux oreilles du marin par des fils spéciaux. En faisant évoluer l'appareil, on se rendra facilement compte de l'origine du signal, qu'il vienne d'un point de la côte ou d'un autre steamer. (Compiled from various sources)
‣ Source : Leong, Michael (2009), “E.S.P.”. Silenced Press.
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