Things not generally Known 



nearly an acre), by means of an iron chain lying upon the ground 

 and stretched round half their circumference. In 1 745, Dr. Wat- 

 son, assisted by several members of the Royal Society, made a 

 series of experiments to ascertain how far electricity could be 

 conveyed by means of conductors. " They caused the shock to 

 pass across the Thames at Westminster Bridge, the circuit being 

 completed by making use of the river for one part of the chain 

 of communication. One end of the wire communicated with 

 the coating of a charged phial, the other being held by the ob- 

 server, who in his other hand held an iron rod which he dipped 

 into the river. On the opposite side of the river stood a gentle- 

 man, who likewise dipped an iron rod in the river with one 

 hand, and in the other held a wire the extremity of which 

 might be brought into contact with the wire of the phial. Upon 

 making the discharge, the shock was felt simultaneously by 

 both the observers." (Priestley's History of Electricity.} Sub- 

 sequently the same parties made experiments near Shooter's 

 Hill, when the wires formed a circuit of four miles, and con- 

 veyed the shock with equal facility, "a distance which without 

 trial," they observed, " was too great to be credited."* These 

 experiments in 1747 established two great principles : 1, that 

 the electric current is transmissible along nearly two miles and 

 a half of iron wire ; 2, that the electric current may be completed 

 by burying the poles in the earth at the above distance. 



In the following year, 1748, Benjamin Franklin performed 

 his celebrated experiments on the banks of the Schuylkill, near 

 Philadelphia ; which being interrupted by the hot weather, they 

 were concluded by a picnic, when spirits were fired by an elec- 

 tric spark sent through a wire in the river, and a turkey was 

 killed by the electric shock, and roasted by the electric jack 

 before a fire kindled by the electrified bottle. 



In the year 1753, there appeared in the Scots' Magazine, vol. 

 xv., definite proposals for the construction' of an electric tele- 

 graph, requiring as many conducting wires as there are letters 

 in the alphabet ; it was also proposed to converse by chimes, 

 by substituting bells for the balls. A similar system of tele- 

 graphing was next invented by Joseph Bozolus, a Jesuit, at 

 Rome ; and next by the great Italian electrician Tiberius Ca- 

 vallo, in his treatise on Electricity. 



In 1787, Arthur Young, when travelling in France, saw a 

 model working telegraph by M. Lomond : " You write two or 

 three words on a paper," says Young; "he takes it with him 

 into a room, and turns a machine enclosed in a cylindrical case, 



* These experiments were performed at the expense of the Royal Society, and 

 cost 10^. 5s. 6d. In the Paper detailing the experiments, printed in the 45th 

 volume of the Philosophical Transactions, occurs the first mention of Dr. Franklin's 

 name, and of his theory of positive and negative electricity. Weld's Hist. Eoya.1 

 Soc. vol. i. p. 467. 



