Chapter 4

Fig. 27.

At the time the instruments were first exhibited in public the results obtained with permanent magnets were not nearly so striking as when a voltaic battery was employed, wherefore we thought it best to exhibit only the latter form of instrument.

The interest excited by the first published accounts of the operation of the telephone led many persons to investigate the subject, and I doubt not that numbers of experimenters have independently discovered that permanent magnets might be employed instead of voltaic batteries. Indeed one gentleman, Professor Dolbear, of Tufts College, not only claims to have discovered the magneto-electric telephone, but I understand charges me with having obtained the idea from him through the medium of a mutual friend.

Fig. 28.

A still more powerful form of apparatus was constructed by using a powerful compound horse-shoe magnet in place of the straight rod whichhad been previously used (see fig. 28). Indeed the sounds produced by means of this instrument were of sufficient loudness to be faintly audible to a large audience, and in this condition the instrument was exhibited in the Essex Institute, in Salem, Massachusetts, on the 12th Feb. 1877, on which occasion a short speech shouted into a similar telephone in Boston, sixteen miles away, was heard by the audience in Salem. The tones of the speaker’s voice were distinctly audible to an audience of 600 people, but the articulation was only distinct at a distance of about 6 feet. On the same occasion, also, a report of the lecture was transmitted by word of mouth from Salem to Boston, and published in the papers the next morning.

Fig. 29.

From the form of telephone shown infig. 27to the present form of the instrument (fig. 29) is but a step. It is in fact the arrangement offig. 27in a portable form, the magnet F H being placed inside the handle and a more convenient form of mouthpiece provided. The arrangement of these instruments upon a telegraphic circuit is shown infig. 30.

Fig. 30.

And here I wish to express my indebtedness to several scientific friends in America for their co-operation and assistance. I wouldspecially mention Professor Peirce and Professor Blake, of Brown University, Dr. Channing, Mr. Clarke, and Mr. Jones. In Providence, Rhode Island, these gentlemen have been carrying on together experiments seeking to perfect the form of apparatus required, and I am happy to record the fact that they communicated to me each new discovery as it was made, and every new step in their investigations. It was, of course, almost inevitable that these gentlemen should retrace much of the ground that had been gone over by me, and so it has happened that many of their discoveries had been anticipated by my own researches; still, the very honourable way in which they from time to time placed before me the results of their discoveries entitles them to my warmest thanks and to my highest esteem. It was always my belief that a certain ratio would be found between the several parts of a telephone, and that the size of the instrument was immaterial; but Professor Peirce was the first to demonstrate the extreme smallness of the magnets which might be employed. And here, in order to show the parallel lines in which we were working, I may mention the fact that two or three days after I had constructed a telephone of the portable form (fig. 29), containing the magnet inside the handle, Dr. Channing was kind enough to send me a pair of telephones of a similar pattern, which had been invented by the Providence experimenters. The convenient form of mouthpiece shown infig. 29, now adopted by me, was invented solely by my friend Professor Peirce. I must also express my obligations to my friend and associate, Mr. Thomas A. Watson, of Salem, Massachusetts, who has for two years past given me his personal assistance in carrying on my researches.

In pursuing my investigations I have ever had one end in view, the practical improvement of electric telegraphy; but I have come across many facts which, while having no direct bearing upon the subject of telegraphy, may yet possess an interest for you.[24]

For instance, I have found that a musical tone proceeds from a piece of plumbago or retort-carbon when an intermittent current of electricity ispassed through it, and I have observed the most curious audible effects produced by the passage of reversed intermittent currents through the human body. A rheotome was placed in circuit with the primary wires of an induction coil, and the fine wires were connected with two strips of brass. One of these strips was held closely against the ear, and a loud sound proceeded from it whenever the other slip was touched with the other hand. The strips of brass were next held one in each hand. The induced currents occasioned a muscular tremor in the fingers. Upon placing my forefinger to my ear a loud crackling noise was audible, seemingly proceeding from the finger itself. A friend who was present placed my finger to his ear, but heard nothing. I requested him to hold the strips himself. He was then distinctly conscious of a noise (which I was unable to perceive) proceeding from his finger. In this case a portion of the induced currents passed through the head of the observer when he placed his ear against his own finger: and it is possible that the sound was occasioned by a vibration of the surfaces of the ear and finger in contact.

When two persons receive a shock from a Ruhmkorff’s coil by clasping hands, each taking hold of one wire of the coil with the free hand, a sound proceeds from the clasped hands. The effect is not produced when the hands are moist. When either of the two touches the body of the other a loud sound comes from the parts in contact. When the arm of one is placed against the arm of the other, the noise produced can be heard at a distance of several feet. In all these cases a slight shock is experienced so long as the contact is preserved. The introduction of a piece of paper between the parts in contact does not materially interfere with the production of the sounds, but the unpleasant effects of the shock are avoided.

When an intermittent current from a Ruhmkorff’s coil is passed through the arms a musical note can be perceived when the ear is closely applied to the arm of the person experimented upon. The sound seems to proceed from the muscles of the fore-arm and from the biceps muscle. Mr. Elisha Gray[25]has also produced audible effects by the passage of electricity through the human body.

An extremely loud musical note is occasioned by the spark of a Ruhmkorff’s coil when the primary circuit is made and broken with sufficient rapidity; when two rheotomes of different pitch are caused simultaneously to open and close the primary circuit a double tone proceeds from the spark.

A curious discovery, which may be of interest to you, has been made by Professor Blake. He constructed a telephone in which a rod of soft iron, about six feet in length, was used instead of a permanent magnet. A friend sang a continuous musical tone into the mouthpiece of a telephone, like that shown infig. 29, which was connected with the soft iron instrument alluded to above. It was found that the loudness of the sound produced in this telephone varied with the direction in which the iron rod was held, and that the maximum effect was produced when the rod was in the position of the dipping-needle. This curious discovery of Professor Blake has been verified by myself.

When a telephone is placed in circuit with a telegraph line, the telephone is found seemingly to emit sounds on its own account. The most extraordinary noises are often produced, the causes of which are at present very obscure. One class of sounds is produced by the inductive influence of neighbouring wires and by leakage from them, the signals of the Morse alphabet passing over neighbouring wires being audible in the telephone, and another class can be traced to earth currents upon the wire, a curious modification of this sound revealing the presence of defective joints in the wire.

Professor Blake informs me that he has been able to use the railroad track for conversational purposes in place of a telegraph wire, and he further states that when only one telephone was connected with the track the sounds of Morse operating were distinctly audible in the telephone, although the nearest telegraph-wires were at least forty feet distant.

Professor Peirce has observed the most curious sounds produced from a telephone in connection with a telegraph wire during the aurora borealis; and I have just heard of a curious phenomenon lately observed by Dr. Channing. In the city of Providence, Rhode Island, there is anoverhouse wire about one mile in extent with a telephone at either end. On one occasion the sound of music and singing was faintly audible in one of the telephones. It seemed as if some one were practising vocal music with a pianoforte accompaniment. The natural supposition was that experiments were being made with the telephone at the other end of the circuit, but upon inquiry this proved not to have been the case. Attention having thus been directed to the phenomenon, a watch was kept upon the instruments, and upon a subsequent occasion the same fact was observed at both ends of the line by Dr. Channing and his friends. It was proved that the sounds continued for about two hours, and usually commenced about the same time. A searching examination of the line disclosed nothing abnormal in its condition, and I am unable to give you any explanation of this curious phenomenon. Dr. Channing has, however, addressed a letter upon the subject to the editor of one of the Providence papers, giving the names of such songs as were recognised, with full details of the observations, in the hope that publicity may lead to the discovery of the performer, and thus afford a solution of the mystery.

My friend Mr. Frederick A. Gower communicated to me a curious observation made by him regarding the slight earth connection required to establish a circuit for the telephone, and together we carried on a series of experiments with rather startling results. We took a couple of telephones and an insulated wire about 100 yards in length into a garden, and were enabled to carry on conversation with the greatest ease when we held in our hands what should have been the earth wire, so that the connection with the ground was formed at either end through our bodies, our feet being clothed with cotton socks and leather boots. The day was fine, and the grass upon which we stood was seemingly perfectly dry. Upon standing upon a gravel walk the vocal sounds, though much diminished, were still perfectly intelligible, and the same result occurred when standing upon a brick wall one foot in height, but no sound was audible when one of us stood upon a block of freestone.

One experiment which we made is so very interesting that I must speak of it in detail. Mr. Gower made earth connection at his end of the line by standing upon a grass plot, whilst at the other end of the line Istood upon a wooden board. I requested Mr. Gower to sing a continuous musical note, and to my surprise the sound was very distinctly audible from the telephone in my hand. Upon examining my feet I discovered that a single blade of grass was bent over the edge of the board, and that my foot touched it. The removal of this blade of grass was followed by the cessation of the sound from the telephone, and I found that the moment I touched with the toe of my boot a blade of grass or the petal of a daisy the sound was again audible.

The question will naturally arise, Through what length of wire can the telephone be used? In reply to this I may say that the maximum amount of resistance through which the undulatory current will pass, and yet retain sufficient force to produce an audible sound at the distant end, has yet to be determined; no difficulty has, however, been experienced in laboratory experiments in conversing through a resistance of 60,000 ohms, which has been the maximum at my disposal. On one occasion, not having a rheostat at hand, I may mention having passed the current through the bodies of sixteen persons, who stood hand in hand. The longest length of real telegraph line through which I have attempted to converse has been about 250 miles. On this occasion no difficulty was experienced so long as parallel lines were not in operation. Sunday was chosen as the day on which it was probable other circuits would be at rest. Conversation was carried on between myself, in New York, and Mr. Thomas A. Watson, in Boston, until the opening of business upon the other wires. When this happened the vocal sounds were very much diminished, but still audible. It seemed, indeed, like talking through a storm. Conversation though possible could be carried on with difficulty, owing to the distracting nature of the interfering currents.

I am informed by my friend Mr. Preece that conversation has been successfully carried on through a submarine cable, sixty miles in length, extending from Dartmouth to the Island of Guernsey, by means of hand telephones similar to that shown infig. 30.

Footnotes:[1]Helmholtz.Die Lehre von dem Tonempfindungen.(English Translation by Alexander J. Ellis,Theory of Tone.)[2]C. G. Page.“The Production of Galvanic Music.” Silliman’s Journ. 1837, xxxii. p. 396; Silliman’s Journ. July, 1837, p. 354; Silliman’s Journ. 1838, xxxiii. p. 118; Bibl. Univ. (new series), 1839, ii. p. 398.[3]J. P. Marrian.Phil. Mag. xxv. p. 382; Inst. 1845, p. 20; Arch. de l’Électr. v. p. 195.[4]W. Beatson.Arch. de l’Électr. v. p. 197; Arch. de Sc. Phys. et Nat. (2d series), ii. p. 113.[5]Gassiot.See “Treatise on Electricity,” by De la Rive, i. p. 300.[6]De la Rive.Treatise on Electricity, i. p. 300; Phil. Mag. xxxv. p. 422; Arch. de l’Électr. v. p. 200; Inst. 1846, p. 83; Comptes Rendus, xx. p. 1287; Comp. Rend. xxii. p. 432; Pogg. Ann. lxxvi. p. 637; Ann. de Chim. et de Phys. xxvi. p. 158.[7]Matteucci.Inst. 1845, p. 315; Arch, de l’Électr. v. 389.[8]Guillemin.Comp. Rend. xxii. p. 264; Inst. 1846, p. 30; Arch. d. Sc. Phys. (2d series), i. p. 191.[9]G. Wertheim.Comp. Rend. xxii. pp. 336, 544; Inst. 1846, pp. 65, 100; Pogg. Ann. lxviii. p. 140; Comp. Rend. xxvi. p. 505; Inst. 1848, p. 142; Ann. de Chim. et de Phys., xxiii. p. 302; Arch. d. Sc. Phys. et Nat. viii. p. 206; Pogg. Ann. lxxvii. p. 43; Berl. Ber. iv. p. 121.[10]Elie Wartmann.Comp. Rend. xxii. p. 544; Phil. Mag. (3d series), xxviii. p. 544; Arch. d. Sc. Phys. et Nat. (2d series), i. p. 419; Inst. 1846, p. 290; Monatscher. d. Berl. Akad. 1846, p. 111.[11]Janniar.Comp. Rend, xxiii. p. 319; Inst. 1846, p. 269; Arch. d. Sc. Phys. et Nat. (2d. series), ii. p. 394.[12]J. P. Joule.Phil. Mag. xxv. pp. 76, 225; Berl. Ber. iii. p. 489.[13]Laborde.Comp. Rend. l. p. 692; Cosmos, xvii. p. 514.[14]Legat.Brix. Z. S. ix. p. 125.[15]Reis.“Téléphonie.” Polytechnic Journ. clxviii. p. 185; Böttger’s Notizbl. 1863, No. 6.[16]J. C. Poggendorff.Pogg. Ann. xcviii. p. 192; Berliner Monatsber. 1856, p. 133; Cosmos, ix. p. 49; Berl. Ber. xii. p. 241; Pogg. Ann. lxxxvii. p. 139.[17]Du Moncel.Exposé, ii. p. 125; also, iii. p. 83.[18]Delezenne.“Sound produced by Magnetization,” Bibl. Univ. (new series), 1841, xvi. p. 406.[19]See London Journ. xxxii. p. 402; Polytechnic Journ. ex. p. 16; Cosmos, iv. p. 43; Glösener—Traité général, &c. p. 350; Dove.-Repert. vi. p. 58; Pogg. Ann. xliii. p. 411; Berl. Ber. i. p. 144; Arch. d. Sc. Phys. et Nat. xvi. p. 406; Kuhn’s Encyclopædia der Physik, pp. 1014-1021.[20]Gore.Proceedings of Royal Society, xii. p. 217.[21]C. G. Page.“Vibration of Trevelyan’s bars by the galvanic current.” Silliman’s Journal, 1850, ix. pp. 105-108.[22]Sullivan.“Currents of Electricity produced by the vibration of Metals,” Phil. Mag. 1845, p. 261; Arch. de l’Électr. x. p. 480.[23]The full description of this figure will be found in Mr. Alexander J. Ellis’s translation of Helmholtz’s work, “Theory of Tone.”[24]SeeResearches in Telephony.—Trans. of American Acad. of Arts and Sciences, vol. xii. p. 1.[25]Elisha Gray.Eng. Pat. Spec. No. 2646, Aug. 1874.

Footnotes:

[1]Helmholtz.Die Lehre von dem Tonempfindungen.(English Translation by Alexander J. Ellis,Theory of Tone.)

[2]C. G. Page.“The Production of Galvanic Music.” Silliman’s Journ. 1837, xxxii. p. 396; Silliman’s Journ. July, 1837, p. 354; Silliman’s Journ. 1838, xxxiii. p. 118; Bibl. Univ. (new series), 1839, ii. p. 398.

[3]J. P. Marrian.Phil. Mag. xxv. p. 382; Inst. 1845, p. 20; Arch. de l’Électr. v. p. 195.

[4]W. Beatson.Arch. de l’Électr. v. p. 197; Arch. de Sc. Phys. et Nat. (2d series), ii. p. 113.

[5]Gassiot.See “Treatise on Electricity,” by De la Rive, i. p. 300.

[6]De la Rive.Treatise on Electricity, i. p. 300; Phil. Mag. xxxv. p. 422; Arch. de l’Électr. v. p. 200; Inst. 1846, p. 83; Comptes Rendus, xx. p. 1287; Comp. Rend. xxii. p. 432; Pogg. Ann. lxxvi. p. 637; Ann. de Chim. et de Phys. xxvi. p. 158.

[7]Matteucci.Inst. 1845, p. 315; Arch, de l’Électr. v. 389.

[8]Guillemin.Comp. Rend. xxii. p. 264; Inst. 1846, p. 30; Arch. d. Sc. Phys. (2d series), i. p. 191.

[9]G. Wertheim.Comp. Rend. xxii. pp. 336, 544; Inst. 1846, pp. 65, 100; Pogg. Ann. lxviii. p. 140; Comp. Rend. xxvi. p. 505; Inst. 1848, p. 142; Ann. de Chim. et de Phys., xxiii. p. 302; Arch. d. Sc. Phys. et Nat. viii. p. 206; Pogg. Ann. lxxvii. p. 43; Berl. Ber. iv. p. 121.

[10]Elie Wartmann.Comp. Rend. xxii. p. 544; Phil. Mag. (3d series), xxviii. p. 544; Arch. d. Sc. Phys. et Nat. (2d series), i. p. 419; Inst. 1846, p. 290; Monatscher. d. Berl. Akad. 1846, p. 111.

[11]Janniar.Comp. Rend, xxiii. p. 319; Inst. 1846, p. 269; Arch. d. Sc. Phys. et Nat. (2d. series), ii. p. 394.

[12]J. P. Joule.Phil. Mag. xxv. pp. 76, 225; Berl. Ber. iii. p. 489.

[13]Laborde.Comp. Rend. l. p. 692; Cosmos, xvii. p. 514.

[14]Legat.Brix. Z. S. ix. p. 125.

[15]Reis.“Téléphonie.” Polytechnic Journ. clxviii. p. 185; Böttger’s Notizbl. 1863, No. 6.

[16]J. C. Poggendorff.Pogg. Ann. xcviii. p. 192; Berliner Monatsber. 1856, p. 133; Cosmos, ix. p. 49; Berl. Ber. xii. p. 241; Pogg. Ann. lxxxvii. p. 139.

[17]Du Moncel.Exposé, ii. p. 125; also, iii. p. 83.

[18]Delezenne.“Sound produced by Magnetization,” Bibl. Univ. (new series), 1841, xvi. p. 406.

[19]See London Journ. xxxii. p. 402; Polytechnic Journ. ex. p. 16; Cosmos, iv. p. 43; Glösener—Traité général, &c. p. 350; Dove.-Repert. vi. p. 58; Pogg. Ann. xliii. p. 411; Berl. Ber. i. p. 144; Arch. d. Sc. Phys. et Nat. xvi. p. 406; Kuhn’s Encyclopædia der Physik, pp. 1014-1021.

[20]Gore.Proceedings of Royal Society, xii. p. 217.

[21]C. G. Page.“Vibration of Trevelyan’s bars by the galvanic current.” Silliman’s Journal, 1850, ix. pp. 105-108.

[22]Sullivan.“Currents of Electricity produced by the vibration of Metals,” Phil. Mag. 1845, p. 261; Arch. de l’Électr. x. p. 480.

[23]The full description of this figure will be found in Mr. Alexander J. Ellis’s translation of Helmholtz’s work, “Theory of Tone.”

[24]SeeResearches in Telephony.—Trans. of American Acad. of Arts and Sciences, vol. xii. p. 1.

[25]Elisha Gray.Eng. Pat. Spec. No. 2646, Aug. 1874.

Back to Index Next