[39] ‘Philosophical Magazine,’ April 1882.
[40] ‘Atti del R. Istituto Veneto di Scienze,’ vol. vi. ser. 5.
[41] Proc. Roy. Soc. No. 218, 1882.
[42] See Proc. Roy. Dubl. Soc. Feb. 17, 1879.
[43] Vide ‘The Electrician,’ Feb. 10, 1883.
[44] Journal Soc. Telegr. Engin. and Electricians, vol. xii. p. 137.
[45] Proc. Physical Soc. vol. ii. p. 259, 1878.
[46] ‘Journal Soc. Telegraphic Engineers,’ vol. iv. p. 117, 1874.
[47] The term “semi-conductor” is very rarely used by electricians, who prefer the term “partial conductor” as being more correct. Moreover, electricians, from Faraday downwards, are practically agreed in calling plumbago a good conductor, and worthy of being classified by reason of its high conductivity along with the metals. The substances known as “semi-conductors” are those given in Ferguson’s ‘Electricity,’ p. 49 (edition of 1873), namely, alcohol, ether, dry-wood, marble, paper, straw, and ice. Mascart and other eminent authorities agree in this classification. It would tax even Mr. Edison’s unrivalled ingenuity to make of these materials a transmitter that should alter its resistance by pressure!
[48] Lüdtge’s German Patent, dated Jan. 12, 1878,describes a “Universal Telephone” in which a tympanum was applied to convey vibrations to an interruptor made of hard coke-carbon.