DISCOURSE OF W. ]!. TAYLOR. 213 



occupation in communicating and diffusing knowledge. Very 

 shortly after his occupation of the academic chair of mathematics 

 and physics, lie turned his attention to the experimental study of 

 that mysterious agency — electricity. Professor Schweigger of 

 Halle, had improved on Oersted's galvanic indicator (of a single 

 wire circuit) by giving the insulated wire a number of turns around 

 an elongated frame longitudinally enclosing the compass needle; 

 and by thus multiplying the effect of the galvanic circuits, had con- 

 verted it into a real measuring instrument — a "galvanometer."* 

 Ampere and Arago of Paris, developing Oersted's announcement 

 of the torsional or equatorial reaction between a galvanic conductor 

 and a magnetic needle, had found that a circulating galvanic cur- 

 rent was capable not only of deflecting a suspended magnet, but of 

 generating magnetism — permanently in sewing needles, and tem- 

 porarily in pieces of iron wire, when placed within a glass tube 

 around which the conjunctive wire of the battery had been wound 

 in a loose helix ; and had thus created the " electro-magnet." f The 

 scientific world was just aroused to the close interrogation of this 

 new marvel, each questioner eager to ascertain its most efficient 

 conditions, and to increase its manifestations. William Sturgeon 

 of Woolwich, England, had extended the discoveries of Ampere 

 and Arago, by dispensing with the glass tube, constructing a "horse- 

 shoe" bar of soft iron (after the form of the usual permanent 

 magnet) coated with a non-conducting substance, and winding the 

 copper conjunctive wire directly upon the horse-shoe; and had thus 



*The inune of (lAi/VANr (as original discoverer of chemico-eleetricity) is usually 

 retained to designate both the current and its generator; although the chemico- 

 electric pile ami battery were really firsl contrived by Volta in 1800. In the same 

 manner Oeksted is generally accounted the discoverer of electro-magnetism, 

 although he never devised an electro-magnet ; and appears not to have been tie first 



even to discover the directive influent fa current on a magnetic needle. Eighteen 



years before Ins announcement, Gian Domenico Romagnosi, a physicist of Tent, 

 published in an Italian newspaper of that city, the Gdzzetla di T)-e?ito, on the 3rd of 

 August, 1802, his observation of the galvanic deflection of the needle. This impor- 

 tant discovery was also published in Professor G. Aldini's "Essai thfiorique et 

 experimental sur le < ralvanisme." 4to. Paris, 1804, p. 191 : ami in Professor J. Izarn's 

 "Manuel du Galvanisme." 8vo. Taris, 1805, sect. ix. p. 120. 



f Annales '/<■ Chimie et de Physique, 1820, vol. xv pp. 93-100. Van Beek of Utrecht, 



in 1821 inverting Abago's experiment, had found that an iron or steel wir tiled 



around a glass tube as a short helix, became magnei ie on passing a charge from a 

 Leyden jar through a straight brass wire placed within the glass tube. Communi- 

 cated by Professor G. Moll. (Brewster's Edinburgh Journal of Science, Jan. 1822, vol. 

 vi. p. 81.) 



