156 



ATMOSPHERICAL ELECTRICITY. 



[1854. 



On the 10 tli of August, 1757, he performed the experiment 

 with magnificent success, obtaining sparks of lightning one inch 

 thick and ten feet in length. Charles, it is said, did most to 

 give popularity and fame to the kite experiment. 



Charles, who was fortunate in having Fresnel as his successor 

 and Fourier as his eulogist in the French Academy, was born at 

 at Baugency on the 12th of November, 1746. He was inspired 

 to undertake physical investigations by the brilliancy of Franklin's 

 career. To this end he left the public service, and lectured on 

 science for thirty years, being honored sometimes by the pres- 

 ence of Franklin and Volta. Franklin complimented his experi- 

 mental skill by confessing that Nature refused nothing to him, 

 but obeyed him as her master. It is worth remembering, as 

 being perhaps partly the secret of his success, that he studied 

 the minutest points of his lectures with remarkable care; and 

 often expended days in preparing an experiment in his laboratory 

 which flashed off before the public in a few minutes. Among 

 several who experimented with the kite, we may mention Cavallo, 

 who discovered as Islington, in 1775, a large amount of electricity 

 in the air when there was no thunder, and only here and there 

 a solitary cloud. About 1800, Cuthbertson tried experiments 

 on atmospherical electricity with a kite. He made the remark- 

 able observation that the spark was very pungent when a long- 

 string was used, and from experiments with an electrical machine 

 he came to' the accurate conclusion, that the increased intensity 

 was caused in some way (now better understood) by the length of 

 the string as such, and not by the greater elevation of which a long- 

 string admitted. When a jar was slightly charged and the 

 spark was only one tenth of an inch in length, it gave a smart 

 shock if the charge was sent through a long string. For at- 

 taining unusual elevations, Cuthbertson conceived the idea of 

 sending out one kite after another, in tandem style, sometimes 

 to the number of three, each with five hundred feet of wire. 

 The opposite currents, which are often encountered at different 

 heights, make this experiment a very difficult one. Sturgeon, 

 of Woolwich, England, made four hundred kite experiments, ex- 

 pending over a period of six years. He describes at length an ex- 

 periment at Addiseombe in March, 1824. When he had half a 

 mile of string out, he obtained a rapid series of sparks, through a 

 plate of air one and a half inches thick. In the afternoon he at- 

 tached the lower end of this string to the back of another kite, so 

 as to let out one quarter of a mile more of string. Now the sparks 

 became painful. At other times, even with three kites deployed 

 in line, the electrical effects were insignificant. In hot and 

 sultry weather, Sturgeon found the shocks violent when the kite 

 had risen no higher than a church-steeple, and the string not 

 even insulated. Sometimes they became so intolerable, that he 

 could not pay out the string through the hand, and was obliged 

 to use a reel. Electric disturbances were felt often when the 

 kite was not within a quarter of a mile of any cloud. These 

 were the effects of electrical induction. Sturgeon remarks that 

 "Sergeant Rudd, of the Royal Artillery, if still alive, remembers 

 well the effect of an electrical wave. Having presented his 

 hand to the kite-string several times without experiencing even 

 a spark, in the Artillery Barrack grounds at Woolwich, he bet>an 

 to laugh at the idea of electric shocks from the air. Shortly, 

 however, I espied a -cloud making its appearance behind the 

 Repository, and on its approach asked the Sergeant to try again. 

 He did so, but before he got his hand near to the string, a dis- 

 charge struck it and sent the sceptic reeling, to the great amuse- 

 ment of his brother non-commissioned officers who were present." 

 On the 29th of March, 1842, Sturgeon floated his kite with 

 three hundred yards of wired cord just before the approach of 

 a hail-storm, when he obtained a rapid succession of sparks 



through an interval of air six inches in length, or a constant 

 stream of fire through a length of three inches. It was no un- 

 usual sight for the string and reel to bristle with purple light, 

 and the blades of grass for yards around to be tipped with tire. 

 Once Sturgeon lost a kite by the melting of the wire nine hun- 

 dred feet from the ground. A cloud was visible, but no 

 thunder was heard. In 1834 a man received a severe shock 

 from a kite-string which he touched with a stick four feet long. 

 This occurred during a hail-storm. On one occasion, Sturgeon 

 received a shock through three feet of dry ribbon, attached as a 

 handle to the kite-string, when no visible cloud was within a 

 mile. The end of the string was tied to a tree, and it was not 

 possible to take down the kite until a cloud far to the windward 

 had passed over to the leeward. And generally, the presence 

 of a cloud makes a decided effect on the electrical activity of 

 the atmosphere. Franklin and Saussure were under the per- 

 suasion that lightning never issued from a lone cloud. But 

 Arago has adduced five cases in which destruction to trees and 

 animals has come forth from this source. As such a cloud ap- 

 proaches the kite, the electrical sparks drawn from the string in- 

 "crease in length and intensity. 



Weekes has objected to the kite experiment as a proper means 

 of studying atmospherical electricity, because it is calculated to 

 give only local phenomena. He thinks that the more general 

 features of the case would be better obtained by horizontal wires 

 of great length, and presenting a large amount of surface to the 

 influence of the air. About 1841, Weekes erected a wire for 

 this purpose at Sandwich, on the south-east coast of England. 

 This wire was stretched over the town, a distance of 1095 feet, 

 and one end was attached to the vane-spindle on the tower of 

 St. Peter, and the other to the vane-spindle ot the tower of St. 

 Clement. The elevation of the wire at the two extremities was 

 one hundred and thirty-six feet above a base line running 

 between the two edifices. Its average elevation above the sea 

 was fifty-five feet. A vertical wire was attached to the middle of 

 this horizontal wire, and descended into the room of the observer. 

 Provision was made to carry the charge, in whole or in part, to 

 a distant well, whenever it became dangerous in magnitude or 

 suited the purpose of the observer to do so. Weekes observes, 

 that, " even the light and feathery aggregations of the summer 

 cloud are sufficient to effect the electroscope, through their in- 

 ductive action on the outstretched wire. And when thunder- 

 clouds were forming, the action was so potent that liquids were 

 chemically decomposed, metals were deflagrated, and large quan- 

 tities of coated surface were charged and discharged in a few 

 seconds. Some inconvenience arose from the weight of birds, 

 particularly of swallows, which settled on the wire. Sometimes 

 they occupied the whole length of wire in a protracted session, 

 debating as it might seem in relation to their autumnal departure 

 for fairer climes. Weekes remarked, that on the 16th of Sep- 

 tember, 1840, during a sudden rain, there were witnessed furious 

 discharges of sparks from ball to ball of his apparatus, though 

 there was but little thunder, and an interval of five or six seconds 

 between the flash and the report showed that that little was a 

 mile distant. Weekes after a time found it necessaiy to confine 

 the horizontal wire near the middle, to protect it from the 

 violence of the winds. Before he did so, it gave out music, as 

 the telegraph-wires are known to do, like a vast ^Eolian string. 

 His neighbors regarded these sounds with superstitious awe, 

 and predicted that no good would come of them. No good did 

 come to Weekes; for they persecuted him in all the little ways 

 which are still possible in an age of freedom and intelligence. 



The apparatus and experiments of Weekes have served to 

 attract attention to observations which Crosse had been making 



