582 PHILOSOPHICAL TRANSACTIONS. [aNNO I76I. 



this letter the hj'pothesis of M. Jallabert of Geneva, a very worthy member of this 

 Society, in regard to the electrical phenomena, is examined ; and such part of it 

 as does not coincide with the ideas of our author, he endeavours to confute by an 

 ingenious series of deductions. The 3d, 4th, and 5th letters are addressed to M. 

 Du Tour, of Riom in Auvergne, who has been a diligent inquirer into the nature 

 and properties of electricity. In the first of these is a careful examination of the 

 validity of the doctrine of plus and minus in bodies electrified. So early as in 

 February 1745, I communicated to the Royal Society an experiment and some 

 deductions from it, which laid the foundation of this doctrine. This experiment, 

 and the deductions in consequence of it, were afterwards printed in the Philos. 

 Trans.* These I explained more at large, both by experiments and ol)servations, 

 in another paper read to the Society in February 1745-6,-|- and were the expe- 

 riments which so early caused me to conceive that there was something in the 

 henomenon of electricity not to be resolved but on statical principles ; and 

 enabled me first to assert that the phenomena in bodies electrified, however simi- 

 lar they might appear, did really arise from the electricity being either greater or 

 less than their natural quantity. This doctrine has since that time been the 

 cause of a variety of experiments, both here and abroad, by which great light has 

 been thrown on this part of natural philosophy. How far our author has been 

 able to overturn this doctrine must be left to other judges to determine. 



In the 4th letter the doctrine of resinous and vitreous electricity is examined. 

 In this letter, as well as in the 5th, a great number both of experiments and de- 

 ductions are produced, not only to weaken the doctrine of plus and minus, but to 

 establish the principle of simultaneous aflfluence and effluence of electric matter ; 

 as if this principle be allowed the doctrine of resinous and vitreous electricity may 

 be reduced to it : as our author is of opinion that there is only one and the same 

 kind of electricity, whether it is natural or artificial ; and that however appear- 

 ances may make it seem to vary, the electricity is one and the same. 



The dth letter is an answer to one of Father Beccaria, professor of experimental 

 philosophy in the university of Turin, published in Italian, in the year 1753, and 

 addressed to the Abbe Nollet. This letter of Pere Beccaria was translated into 

 French, and published at Paris in 1/54, by M. Delor, with many additions and 

 annotations. It contains a very great number of curious experiments and obser- 

 vations, both on artificial and natural electricity ; many of which are brought to 

 prove the validity of the doctrine of our worthy member Dr. Franklin, in opposi- 

 •ion to that of the Abbe Nollet. More particularly he endeavours to confute the 

 Abbe's opinion, in regard to the affluence of the electric matter, which the Abbe 

 has by experiments and obser\'ations ingeniously endeavoured to confirm. Pere 



• Vide Vol. xhiv. p. 739- 

 + See Phil, Trans. Vol. xlv. p. 93—101 . 



