ELECTRICITY. 113 



the oilier hand an iron rod. This rod he dipped into the river, when instantly 

 the shock was received by both persons, the electric fluid having passed over 

 the bridge, through the body of the person on the other side, through the wa- 

 tei across the river, through the rod held by the other person, and through his 

 body to the exterior coating of the jar. Familiar as such a fact may now ap- 

 pear, it is impossible to convey an adequate idea of the amazement, bordering 

 on incredulity, with which it was at that time witnessed. 



The next experiment was made at Stoke Newington, near London, where a 

 circuit of about two miles in length was formed, consisting, as in the former 

 case, partly of water and partly of wire. In one case there were about 2,800 

 feet of wire, and 8,000 feet of water. The result was the same as in the case 

 of the experiment at Westminster bridge. In this case, on repeating the ex- 

 periment, the rods, instead of being dipped in the water, were merely fixed in 

 the soil at about twenty feet from the water's edge, when it was found that the 

 shock was equally transmitted. This created a doubt whether, in the former 

 case, the shock might not have been conveyed through the ground between the 

 two rods, instead of passing through the water, and subsequent experiments 

 proved that such was the case. 



The same experiments were repeated at Highbury, and finally at Shooter's 

 Hill, in August, 1747. At the latter place the wire from the inside of the jar 

 was 6,732 feet, and that which touched the outside coating was 3,868 feet long. 

 The observers placed at the extremity of these wires, were two miles distant 

 from each other. The circuit, therefore, consisted of two miles of wire, and 

 two miles of soil or ground, the latter being the space between the two observ- 

 ers. The result of the experiment proved that no observable interval elapsed 

 between the moments at which each observer sustained the shock. In this 

 experiment the wires were insulated by being supported on rods of baked 

 wood. 



We shall here pass over a variety of experiments made in England, France, 

 and Germany, on the effects of electricity on organized bodies, and on some 

 proposed medical applications of that agent ; such researches not having led 

 to any general principles affecting the real advancement of the science. 



Passing from the analysis of the confused experimental labors of his imme- 

 diate predecessors, labors which contributed so little to the development of the 

 nature and laws of electrical phenomena, to the researches of Franklin, is like 

 the transition from the mists and obscurity of morning twilight to the unclouded 

 splendor of the noontide sun. It was in the summer of the year 1747, that a 

 fortuitous circumstance, happily for the progress of knowledge, first drew the 

 attention of this truly great and good man, and (as he afterward proved) acute 

 philosopher, to the subject of electricity. Mr. Peter Collinson, a fellow of the 

 Royal Society of London, and a gentleman who took much interest in scien- 

 tific affairs, made a communication to the Literary Society of Philadelphia, ex- 

 plaining what had been recently done in England in electrical experiments, and 

 with his letter he sent a present of one of the glass tubes then commonly used 

 to excite electricity, with directions for its use. Previous to this time, Frank- 

 lin does not appear to have ever given his attention to physical science. Never- 

 theless, he now commenced repeating the European experiments with all the 

 ardor of an enthusiast, and extending, varying, and adapting them to the de- 

 velopment of great general laws, with all the skill and sagacity of a practised 

 experimental philosopher. Within the brief period of four months after the 

 arrival of the tube, he commenced a series of letters to Mr. Collinson, in which 

 are related a body of discoveries, which for the high generality of the laws 

 they unfolded, the surpassing beauty and clearness of the experimental demon- 

 strations on which they were based, and their intimate connexion with the 



