HENRY AXD THE TELEGRAPH. 263 



discoverer while tliey deify the artisan. When Galvani about a cen- 

 tury ago (17SG) first opened slightly the door to one of nature's mar- 

 vels, that large community ever distinguished by the vigor of its com- 

 mon sense and the practical solidity of its judgment, asked with ready 

 instinct the wise and ancient question, " What is the use of it V' And a 

 majority of those who recognized the experimenter's appearance on the 

 streets of Bologna, pointed him out as the '• frog philosopher," Their 

 descendants and rejiresentatives at the present day have neither lost — 

 nor gained in wit.* 



It is proposed to notice the development of the electric telegrai)h 

 somewhat at length, in order to exhibit more cleaily the i^recise nature 

 and value of Henry's contribution to its in^actical establishment and 

 success. This survey naturally divides itself into a chronological re- 

 view of the successive though overlai^iiing applications — of frictional or 

 mechanical electricity (lirst suggested by Franklin ? or by Lesage ? about 

 the middle of the last century) ; f of galvanism or chemical electricity 

 (first suggested by Scemmering in 1808) ; and of galvano-magnetism 

 (fii-st suggested by Amjjere in 1820). | 



Among the numerous flights of imagination by which genius has fre- 

 quently anticipated the achievements of her more deliberate and cautious 

 sister — earth-walking reason, none is perhaps more striking than the ro- 

 mantic conception by Famianus Strada, of Eome, in the early part of the 

 seventeenth century, of an intercourse maintained between separated 

 friends by means of two sympathetic magnetic compasses, whereby the 

 indications on the dial given by one, were instantly made visible to the 

 other. § 



* On tlie value of abstract science, see " Supplement," Note A. 



t Mr. Stephen Gray, in a letter to Dr. Cromwell Mortimer, secretary of the Royal Soci- 

 ety of London, dated February 8, 1731, recited among numerous electrical experiments, 

 the passage of sparks and the excitation of an electroscope, effected through 293 feet of 

 ■wire suspended by silk, in 1729 ; through 66(5 feet on July 3 of that year ; a week or 

 two later, through 765 feet; and in August, 1730, through 8S6 feet of wire. (Fhil. 

 Trans. E. S. 1731, vol. xsxvii. No. 417, pp. 29, 31, and 44.) These experiments were 

 made however for the purpose of determining conductive capacity, without any view 

 of employing the indications for signals. 



A letter was published in the Scots^ Magazine, dated Renfrew, February 1, 1753, and 

 signed " C. M.," which, under the title "'An expeditions method of conveying intelli- 

 gence," proposed the sns])ension between two distant points of a number of insulated 

 wires (equal to the niuuber of letters in the alphabet), through which electrical dis- 

 charges should separately exhibit themselves by the diverging balls of an electroscope, 

 or the striking of a bell by the attraction of a charged ball. The author of the com- 

 numication was supposed by Sir David Brew.ster to be a Charles ^Marshall, of Paisley. 

 (TIw Enfi'uwa; London, Dee. 24, 1858, vol. vi., p. 484.) It is probable that G. L. Le- 

 sage. of Geneva, entertained the project of an electric telegraph as early as the middle 

 of the last century. It Avas therefore rather the impulse of an age, than the inspira- 

 •fion of an individual. 



jThe application of magneto-electricity, presenting no essential diftVrencesfrom the 

 itse of galvano-electricity, (for which it is souietimes substituted,) reiiuires no special 

 notice. Still less noteworthy is the project of thermo-electricity as the moror. 



^ Prolusiones Jcademica-: by F. Strada, quarto, Rome, 1617, lib. ii, prolusio 6. A 

 century later, (but still a third of a century before man dreamed of electric telegraphs, ) 

 Joseph Addison presented the fidlowing ver.siou of this fairytale: '-Strada. in one 

 of his Prolusions, gives an account of a chimerical correspondence between two 

 fi'ieuds by the help of a certain loadstone which had such a virtue in it that if it 



