VOL. XLVIII.] PHILOSOPHICAL TRANSACTIONS, 37* 



has gnen on the same subjects, it might be imagined, if he were silent on this 

 head, that he had given up his former opinions. This has been one motive for 

 the present publication, which the author is desirous should be considered, less 

 as a criticism on Mr. Franklin's doctrine, than as a defence of his own. 



In some parts of these letters, the author mentions an electricity, which is very 

 often, and perhaps always, in our atmosphere, when there is no appearance of 

 thunder. He sjjeaks of this, as if he only suspected it, and in a manner as if it 

 wanted confirmation. He was then unacquainted with some decisive experiments 

 made on this subject by le Monnier,* at St. Germain-en-laye, and which have 

 been just published. He now considers, .as a thing certain, that electricity is a 

 very common meteor, which may manifest itself, when the weather is most se- 

 rene ; and that thunder is, strictly speaking, only one of its modifications, which 

 renders it more sensible to us. 



The Abbe Nollet's treatise contains Q letters; 6 of which are addressed to Mr. 

 Franklin, one to Mad'"- Ardinghelli, who, when only l6 years old, translated 

 Dr. Hales's treatise of Ha^mastatics into Italian, and added to it some very inge- 

 nious remarks ; one to Mr. Jallabert of Geneva, and one to Mr. Boze of Wit- 

 temberg : to these are added some experiments in electricity, made in support 

 of opinions, laid down in this work, in the presence of Messrs Bouguer, de 

 Montigny, de Courtivron, d'Alembert, and le Roi, who were appointed by the 

 Royal Academy of Sciences for that purpose. 



In the first letter the author gives his correspondent Mad"'' Ardinghelli an 

 account of the discoveries in electricity in the year 1732 ; among which he takes 

 particular notice of the experiment made on May 10, at Marly-la-ville, in con- 

 sequence of Mr. Franklin's hypothesis ; when pointed non-electrics, supported 

 by electrics per se, gave manifest signs of electricity during a thunder storm. 

 This experiment, in the letters to Mr. Collinson, Mr. Franklin had proposed, 

 but, as far as may be judged, had not then carried into execution. The expe- 

 riment of Marly-la-ville was soon after verified by le Monnier at St. GJermain- 

 en-laye, who found further, first, that the like effects were produced, whether 

 the iron rods were pointed, or not ; and that it was indifferent, whether their 

 position was horizontal or not. Secondly, that thunder electrized not only iron, 

 but also wood, living bodies, and other electrizable substances. Thirdly, that 

 it was not absolutely necessary to place these botlies at the tops of buildings ; 

 but that it was sufficient for them to be placed about 4 feet from the ground in 

 an open situation, and at some distance from large buildings. Fourthly, 

 that bodies electrized in this manner, produced the like phenomena with those 

 electrized by glass after the usual manner. It was afterwards discovered, that 



• In a memoir read to the Royal Academy of Sciences at Paris, Nov. 15, 1752. — Orig. 



