It was, however, shown by Dr. Seebeck that the power of multiplication does not increase with the number of windings in the uniting wire, for the resistance to transmission naturally increases with the length of the wire, thus diminishing its conducting power.
To his new instrument Schweigger gave the name of electro-magnetic multiplier (multiplicator) or galvanometer multiplier, and it has become the most important for indicating and measuring the strength of the galvanic current.
Prof. W. B. Rogers says that Schweigger’s apparatus as improved by Nobili (Ital. Soc. Mem., Vol. XX. p. 173) became indispensable in the measurement of current electricity, and that through the later improvements given it by Sir William Thomson (also by Du Bois Reymond), it has been made one of the most perfect and delicate of all known means of measuring force. Schweigger’s multipliers with improvements made thereon by Oersted and Nobili are illustrated at p. 642, Vol. XXI of the eighth “Ency. Britannica,” where reference is made to drawings on a large scale shown at Plate 522, article “Thermo-Electricity,” of the “Edinburgh Encyclopædia.”
According to a footnote, p. 273 of “Report Smithsonian Inst.” for 1878, Schweigger’s multiplier is alluded to in the “Additions to Oersted’s Electroma-gnetic Experiments,” a memoir read at the Naturforschende Gesellschaft at Halle, September 16 and November 4, 1820. An abstract of this paper was published in the Allgemeine Literatur-Zeitung of Halle (4to), November 1820, No. 296, Vol. III. col. 621–624, whilst the full memoir appeared in the Journal für Chemie und Physik, 1821, Vol. XXXI. pp. 1–17; and “Additional Remarks ...” by Dr. Schweigger, in the same volume, pp. 35–41. It is further stated in the afore-mentioned note that:
“A galvanometer of somewhat different form, having a vertical helix and employing an unmagnetized needle, was very shortly afterward independently devised by Johann Christian Poggendorff, of Berlin; and as he preceded Schweigger in publishing an account of it, he is sometimes regarded as the original inventor. Schweigger designated his device an ‘Electro-magnetic Multiplicator’; Poggendorff designated his arrangement a ‘Galvano-magnetic Condensator.’ Prof. Oersted remarks: ‘Immediately after the discovery of electro-magnetism, M. Schweigger, professor at Halle, invented an apparatus admirably adapted for exhibiting by means of the magnetic needle the feeblest electric currents.... M. Poggendorff, a distinguished young savant, of Berlin, constructed an electro-magnetic multiplier very shortly after M. Schweigger, with which he made some striking experiments. M. Poggendorff’s work having been cited in a book on electro-magnetism by the celebrated M. Erman (published immediately after the discovery of these phenomena), became known to several philosophers before that of M. Schweigger’ (Annales de Chimie et de Physique, 1823, Vol. XXII. pp. 358–360).
“The researches of Schweigger and Bart leave us little or no doubt that the ancients were well acquainted with the mutual attraction of iron and the lodestone, as well as with the positive and negative properties of electricity, by whatever name they may have called it. The reciprocal magnetic relations to the planetary orbs, which are all magnets, was with them an accepted fact, and aerolites were not only called by them magnetic stones, but used in the Mysteries for purposes to which we now apply the magnet.”
References.—“Isis Unveiled,” Vol. I. pp. 281, 282. See also Annales de Chimie et de Physique, 1816, Vol. II. pp. 84, 86; Thos. Thomson, “An Outline of the Sciences ...” London, 1830, Chap. XV. p. 564; “Encycl. Brit.,” seventh edition, “Voltaic Electricity,” p. 687; Polytechnisches Centralblatt; Sc. Am. Supp., No. 404; Sturgeon’s “Scientific Researches,” Bury, 1850, p. 19; L. F. Kaemtz, Phil. Mag., Vol. LXII. p. 441; Poggendorff, Vol. II. pp. 873–875; Du Moncel, “Exposé ...” Vol. III; Whewell’s “Hist. of Ind. Sci.,” Vol. II. p. 251; “Abhandl. d. Naturf. Gesellsch. zu Halle” for 1853–1856; Schweigger’s Journal für Chemie und Physik, Vol. II. part iv. pp. 424–434; Vol. X for 1814 and Vol. XXXVIII for 1823; “Cat. Sc. Papers Roy. Soc.,” Vol. V. pp. 589–592; “Bibl. Britan.,” Vol. XVI, N.S., 1821, p. 197; Larousse, Vol. XIV. pp. 386–387. Edinburgh Philosophical Journal, July 1821, Vol. V. p. 113. For Seebeck, see Phil. Mag., Vol. LXI, 1823, p. 146. For Poggendorff, see “Cat. Sc. Pap. Roy. Soc.,” Vol. IV. pp. 952–956; Vol. VIII. pp. 638–640; “Bibl. Britan.,” Vol. XVIII, N.S., 1821, p. 195; Pogg., “Annalen,” Vol. CLX (biography).
In the editorship of Schweigger’s Journal, which followed Gehlen’s Journal, Mr. J. S. C. Schweigger was assisted, from 1828, by Franz W. Schweigger-Seidel, who was the author of “Lit. d. Math. Natur.,” published in 1828. (For the joint magnetic work of J. S. C. Schweigger and Wilhelm Pfaff, see Jour. f. Ch. u. Ph., Band X. heft i. for 1814.)
A.D. 1811.—Monsieur Dessaignes is first to establish a relation between electricity and phosphorescence, as is shown in the extract published in London from the Memoir which he had presented two years before to the French Institute. The general view he takes is that phosphorescence is produced by a particular fluid, which is set in motion by light, by heat, by electricity, as well as by friction, and that it is dissipated by overheating or by too long exposure to light.
It is asserted by Fahie (“Hist. of El. Tel.,” pp. xiv, 297) that it was Dessaignes and not Seebeck who first discovered thermo-electricity. “Dessaignes,” he says, “showed us how difference of temperature or heat could produce electricity.” This was in 1815, or six years before Seebeck, who is always credited with the observation (Bostock’s “History of Galvanism,” London, 1818, p. 101). Many observations bearing on thermo-electricity had been made even long before Dessaignes.... In 1759 Æpinus called attention to the same phenomena, and pointed out that electricity of opposite kinds was developed at opposite ends of the crystal (tourmaline). In 1760 Canton observed the same properties in the topaz; and between 1789 and 1791 Haüy showed the thermo-electric properties of various other substances, as mesotype, prehnite, Iceland spar, and boracite.