[2] Some little-known but delightful observations in the prehistory of electromagnetism are described in a letter written by G. W. SCHILLING from London to the Berlin Academy on July 8, 1769, published as "Sur les phenomenes de l'Anguleil Tremblante" [_Nouveaux Memoires de l'Academie Royale des Sciences et Belles-Lettres_, 1770 (Berlin, 1772), pp. 68-74], translated to French from the original German. The letter recounts a mult.i.tude of experiments with various electric eels. The two observations of electromagnetic interest are that a piece of iron held by the hand in the eel's tank could be felt quivering even when the fish was stationary several inches away, and a compa.s.s needle showed a deflection, both in the water near the fish, and outside the tank, also with the fish stationary.

[3] ABRAHAM BENNET, _Philosophical Transactions of the Royal Society of London_ (1787), p. 26.

[4] Op. cit. (footnote 1), p. 403.

[5] _Philosophical Magazine_ (1800), vol. 7, pp. 289-311. [For a facsimile reprint, see _Galvani-Volta_ (Bern Dibner's Burndy Library Publication No. 7), Norwalk, Connecticut, 1952.]

[6] MICHAEL FARADAY, _Experimental Researches in Electricity_, vol. 1 (London, 1839), paragraph 739, dated January 1834.

[7] Ibid., sec. 741.

[8] JAMES c.u.mMING, "On the Application of Magnetism as a Measure of Electricity," _Transactions of the Cambridge Philosophical Society_ (1821), vol. 1, pp. 282-286. [Also published in _Philosophical Magazine_ (1822), vol. 60, pp. 253-257.]

[9] H. C. OERSTED, _Experimenta Circa Effectum Conflictus Electrici in Ac.u.m Magneticam_ (Copenhagen, July 21, 1820).

[10] Full details of Oersted's work and publications are in _Oersted and the Discovery of Electromagnetism_ (Bern Dibner's Burndy Library Publication No. 18), Norwalk, Connecticut, 1961. The original Latin version and first English translation are reproduced in _Isis_ (1928), vol. 34, pp. 435-444.

[11] A. M. AMPeRE, _Annales de Chimie et de Physique_ (1820), vol. 15, p. 67. The word "galvanometer" had been used much earlier by BISCHOF, "On Galvanism and its Medical Applications," _The Medical and Physical Journal_ (1802), vol 7, p. 529, for a form of goldleaf electroscope shown here in figure 2, but this use of the word does not seem to have been adopted by others.

[12] Op. cit. (footnote 6), paragraph 283, dated January 1833. A similar att.i.tude was expressed in the same year by CHRISTIE, _Philosophical Transactions of the Royal Society of London_ (1833), vol. 123, p. 96: "I adopt the word current as a convenient mode of expression, ... but I would not be considered as adopting any theoretical views on the subject...."

[13] Some prominent examples of this brevity of treatment are in E.

HOPPE, _Geschichte der Elektrizitat_ (Leipzig, 1884); O. MAHR, _Geschichtliche Einzeldarstellungen aus der Elektrotechnik_ (Berlin, 1941); R. S. WHIPPLE, "The Evolution of the Galvonometer," _Journal of Scientific Instruments_ (1934), vol. 7, pp. 37-43; WILLIAM STURGEON, _Scientific Researches_ (Bury, 1850); A. W. HUMPHREYS, "The Development of the Conception and Measurement of Electric Current," _Annals of Science_ (1937), vol. 2, pp. 164-178.

[14] M. SPETER, "Klarung der Multiplikator-Prioritatsfrage Schweigger-Poggendorf," _Zeitschrift fur Instrumentenkunde_ (1937) vol.

57, pp. 29-32.

[15] T. SEEBECK, "uber den Magnetismus der Galvanischen Kette,"

_Abhandlungen der Koenigliche Akademie der Wissenschaften zu Berlin_ (1820-1821), pp. 289-346. The phrase "Schweigger's multiplier" is used on page 319. The many experiments described in this paper added little or nothing to contemporary appreciation of the multiplier as an instrument.

[16] J. S. C. SCHWEIGGER, _Journal fur Chemie und Physik_ (1821), vol.

31, pp. 1-18, 35-42. Pages 1-6 are the paper presented in Halle on September 16, 1820; pages 7-18 are the paper presented in Halle on November 4, 1820, and pages 35-42 are "a few additional words." The preface to the whole volume is dated January 1, 1821. A somewhat earlier public announcement referring to Schweigger's discovery appeared in the _Allgemeine Literatur-Zeitung_ (November 1820), no. 296, cols. 622-624, but this was lacking in detail and seems not to have been noticed by any scientists.

[17] P. ERMAN, _Umrisse zu den physischen Verhaltnissen des von Herrn Prof. Oersted entdeckten elektro-chemischen Magnetismus_ (Berlin, 1821).

Hoppe (footnote 13) states that Erman's book was published in May; however, it is referred to in a letter dated April 3, 1821, by RASCHIG, _Annalen der Physik_ (1821), vol. 67, pp. 427-436.

[18] Op. cit. (footnote 16), vol. 32, pp. 38-50.

[19] _Annalen der Physik_ (1821), vol. 67, pp. 382-426, and footnote on pages 429-430 of same volume. The footnote accompanies the article by Raschig mentioned in footnote 17.

[20] H. C. OERSTED, "Sur le Multiplier electro-magnetique de M.

Schweigger, et sur quelques applications qu'on en a faites," _Annales de Chimie et de Physique_ (1823), vol. 22, pp. 358-365.

[21] "Versuche mit dem electrisch-magnetischen Multiplicator," _Annalen der Physik_ (1821), vol. 67, pp. 427-436.

[22] _Transactions of the Cambridge Philosophical Society_ (1821), vol.

1, pp. 269-278.

[23] Op. cit. (footnote 8).

[24] The German word _Kette_ has been translated as "circuit"

throughout. Although the equivalence of these words is clear, for example, in Ohm's work of 1826, the context in which _Kette_ is sometimes used in 1820 and 1821 indicates that the concept of a "circuit," in the sense of the wiring external to the source of electricity, has not been established. The wiring is regarded more as something incidental, used to "close" the cell, the cell being considered essentially the whole of the apparatus. This view underlies the many attempts to correlate the Oersted phenomena with cell materials and design, and with the use of such terms as "chemical magnetism" by Erman and others.

[25] The reference here is to the Oersted-type experiments described in two papers by authors other than Schweigger on pages 19 to 34 of the volume.

[26] Op. cit. (footnote 19), pp. 422-426.

[27] One "line" seems to have been about 1/12 inch.

[28] J. G. POGGENDORF, "Physisch-chemische Untersuchungen zur naheren Kenntniss des Magnetismus der voltaischen Saule," _Isis von Oken_ (1821), vol. 8, pp. 687-710. Most of Poggendorf's numerical data is also in C. H. PFAFF, _Der Elektromagnetismus_ (Hamburg, 1824), along with some of Pfaff's own work.

[29] Reported in _Annales de Chimie et de Physique_ (1820), vol. 15, pp.

222-223.

[30] "On the Development of Electro-Magnetism by Heat," _Transactions of the Cambridge Philosophical Society_ (1823), vol. 2, pp. 47-76.

[31] "Account of the New Galvano-Magnetic Condenser invented by M.

Poggendorf of Berlin," _Edinburgh Philosophical Journal_ (July 1821), vol. 5, pp. 112-113.