292 ATMOSPHERIC ELECTRICITY. 



experiment was made l3y Franklin,* in June, 1752, by uniting two 

 sticks in the form of a cross, to which he fastened the four corners of 

 a silk handkerchief. This kite, surmounted by a pointed iron wire, 

 was held by a hempen cord terminating in a thread of silk, and a key 

 attached between the cord and the silk thread served for a conductor, 

 by which the electricity, descending along the cord, might be drawn off. 



This experiment was repeated in France, in a more perfect manner, 

 by De Eomas,t of Nerae, who furnished the cord of a paper kite, seven 

 feet high by three broad, with very fine metallic wire, in order to render 

 it a better conductor of electricity. Moreover, instead of drawing forth 

 the sparks with his finger, which might expose the observer himself to 

 the discharge, he made use of a receiver connected with the ground 

 by a chain. Having taken all the precautions which an enlightened 

 prudence could suggest, De Eomas ventured to launch forth this ap- 

 jDaratus, thus improved, iuto the most stormy clouds; a,nd in one of his 

 experiments, during a storm attended with little rain or visible light- 

 ning, he, for hours, continued to receive flashes or sparks of electricity 

 ten feet long. "■ Imagine to yourself," he wrote to the Abbe Nollet,^ 

 " flashes of fire nine or ten feet long, and an inch in diameter, with a 

 report as loud as that of a pistol. In less than an hour I had cer- 

 tainly thirty of these flashes, and thousands of lesser ones. But what 

 gave me the greatest pleasure in this new spectacle was that these 

 great discharges were spontaneous, and that, in spite of the abundance 

 of the electric fluid of which they were composed, they constantly fell 

 on the nearest conducting bi dy. This uniformity of result gave me 

 so much confidence, that I ventured to draw the fluid with my 

 discharger, even at the time that the storm was quite violent; and 

 although the glass arras of this instrument were only two feet long I 

 conducted where I wished, without feeling the slightest agitation in 

 my hand, streams of fire which were seven or eight inches in length." 



These details show us bow great is the uanger which attend ex- 

 periments 'of this kind. The scientist Charles, § .in order to avoid 

 touching the cord of the kite in letting it off, rolled it around a cylin- 

 der, which he turned by an insulated crank. The cylinder itself 

 was mounted on four pillars of glass. While he wound the cord he 

 established a communication between the cylinder and the ground by 

 means of a chain which terminated in large iron pickets buried in 

 the moist earth; and when the apparatus was insulated he took care 

 to keep himself at a greater distance than these pickets, or in general 

 the nearer conducting bodies, so that if a discharge should happen it 

 might be attracted to them. To attain the same object De Romas|! 

 constructed an apparatus known by the name of the electric chariot, 

 by means of which he could let ofi' the cord of his kite without running 

 any risk, even when the storm was the most violent. 



Among the observers who experimented on atmospheric electricity 



* Experiments and Observations on Electricity, p. 111. 



f Memoires des Savants Etrang., torn. 11, p. 394, 1755. 



% Memoires des h^avants' Etrang., torn. IV, p. 514, 17G3. 



§ Traits de Ph. Experim. efc Matliem., par Biot, torn. 11. p. 446. Paris, 1816. 



[] Diction, de Physiuue, par Brisson, torn. II, p. 174. Paris, ISOO. 



