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 I stood 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 in fig. 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.