MaechIS, 1898.] 



SCIENCE. 



367 



value. The recent applications will be re- 

 ferred to later. 



The mathematical theory of electrostatics 

 and magnetism was greatly extended about 

 this time by Thomson and others, and re- 

 ceived its most complete statement at the 

 hands of Maxwell in his papers read before 

 the Royal Society and in his book, published 

 in 1873, but still the standard of reference. 

 Very little has since been discovered 

 which was not foreshadowed by Maxwell's 

 theory or contained in his equations, which 

 have been found general enough to cover 

 almost everything, although experiment 

 has generally been necessary' to suggest the 

 consequences of the theory. 



The practical applications of electricity 

 have played a most important part in the 

 development of the subject during the last 

 sixty years. Indeed, a great part of the 

 work of these years has had some practical 

 application in view. One of the first of 

 these practical applications was that of 

 telegraphy. 



The telegraph, being one of the earliest of 

 the practical developments, naturally had a 

 great effect in stimulating the advance in 

 knowledge of electricity, and hence I give a 

 somewhat fuller sketch of the early history, 

 that space will permit for the later applica- 

 tions. 



The discovery of Stephen Gray, in 1829, 

 that the electrical influence could be con- 

 veyed to a distance by means of an insulated 

 wire, is probably the first of direct influence 

 in connection with telegraphy. As a result 

 of this discovery and the investigations 

 which followed it, a considerable number of 

 proposals were made as to the use of the 

 electrical force for the transmission of intel- 

 ligence. The first of these of which I have 

 found any record was made in 1753 by 

 Charles Morrison, a Scotchman, and then 

 followed other proposals for electrostatic 

 telegraphs by Bozolus in 1767, by Le Sage 

 in 1774, by Lomond in 1787, by Betancourt 



in the same year, by Eeizen in 1794, by 

 Cavalla in 1795 and by Ronalds in 1816. 



The discovery of voltaic electricity, and 

 most directly the discovery of Nicholson 

 and Carlisle of electrolysis gave rise to an- 

 other group of proposals for the application 

 of this discovery to the production of teleg- 

 raphy. Among those may be mentioned 

 that of Sommering in 1809, of Coxe in 1810 

 and of Sharpe in 1813. In more recent 

 years, of course, the same application ap- 

 pears in the chemical telegraphs, some of 

 which are capable of giving very satisfac- 

 tory results and great speed. 



The discovery which had the greatest in- 

 fluence on the development of telegraphy 

 was that of Oersted, supplemented by the 

 work of Schweigger and Ampere. Ampere 

 proposed a multiple-wire telegraph with 

 galvanoscope indicators in 1820, and a 

 modification was constructed by Ritchie. 

 A single-circuit telegraph of this character 

 was invented by Tribaoillet, but didn't 

 come into use. In 1832 Schilling's five- 

 needle telegraph appeared, and he, also, 

 used a single-needle instrument, but his 

 early death stopped further progress. In 

 1833 Schilling's telegraph was developed, 

 to some extent, by Gauss and Weber, who 

 used it for experimental purposes. The fol- 

 lowing quotation, referring to Gauss and 

 Weber's telegraph, from Poggendorfs An- 

 nalen, is of considerable historical interest : 



" There is, in connection with these ar- 

 rangements, a great and until now in its 

 way novel project, for which we are in- 

 debted to Professor Weber. This gentle- 

 men erected, during the past year, a double- 

 wire line over the houses of the town 

 (Gottingen) , from the Physical Cabinet to 

 the Observatory, and lately a continuation 

 from the latter building to the Magnetic 

 Observatory. Thus, an immense galvanic 

 chain is formed, in which the galvanic cur- 

 rent, the two multipliers at the ends being 

 included, has to travel a distance of nearly 



