224 THE DEVELOPMENT OF ELECTRICAL SCIENCE. 



extended about this time by Thomson and others, and received 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 equa- 

 tions, which have been found general enough to cover almost every- 

 thing, although experiment has generally been necessary to suggest 

 the consequences of the theory. 



The practical applications of electricity have played a most impor- 

 tant 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 its early 

 history than space will permit for the later applications. 



The discovery of Stephen Gray, in 1729, that the electrical influence 

 could be conveyed 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 intelligence. The first of these 

 of which I have found any record was made in 1753 by Charles Mor- 

 rison, 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 Reizen 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 another group of 

 proposals for the application of this discovery to the production of 

 telegraphy. 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 appears in the chemical telegraphs, 

 some of which are capable of giving very satisfactory results and great 

 speed. 



The discovery which had the greatest influence on the development 

 of telegraphy was that of Oersted, supplemented by the work ot 

 Schweigger and Ampere. Ampere proposed a multiple- wire telegraph 

 with galvanoscope indicators in 1820, and a modification was con- 

 structed by Ritchie. A single-circuit telegraph of this character was 

 invented by Tribaoillet, but did not come into use. In 1832 Schilling's 

 five-needle telegraph appeared, and he also used a single-needle instru- 

 ment, 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 following quotation, referring 



