3A PHILOSOPHICAL TRANSACTIONS. [aNNO \770. 



in the flight following these experiments, endless were the schemes that occurred 

 to him of accounting for them, and the methods with which he proposed to 

 diversify them the next morning, in order to find out the cause of this strange 

 phenomenon. Accordingly, he was no sooner at liberty to attend to this experi- 

 ment; but repeating it with some difference in the disposition of the apparatus, 

 he observed that on every discharge a slight motion was given to the threads 

 that hung from the insulated tube. On this the impossibility of an electric spark, 

 neither giving nor taking any thing from an insulated body, contrary to his most 

 attentive observation, and that of his assistants, he concluded that some motion 

 must have been given to the threads the day before; especially when he found 

 that in these later experiments the communicated electricity was always positive, 

 the same with that of the inside of the jar; but the quantity of it was so small, 

 that the most exquisite contrivance was necessary to ascertain the nature of it; 

 for though on this occasion the lateral spark was near a quarter of an inch in 

 length, the threads on the insulated tube could only be made, by the explosion, 

 to change their position, from leaning a little one way, to leaning as mucli the 

 other, in the neighbourhood of an insulated brass rod, loaded with a small quan- 

 tity of positive or negative electricity. 



Dr. P. could not help however being surprized, that so large a spark should 

 give no more electricity to the insulated tube than it appeared to have done; 

 when, in other circumstances, a spark ten times less than this would have made 

 a great and permanent alteration: yet improbable as these circumstances were, 

 he entertained no doubt at that time, but that these insulated bodies were elec- 

 trified, either positively or negatively, according as the inside of the jar was po- 

 sitive or negative, by this lateral explosion, though the degree was exceedingly 

 small; and he continued in this persuasion the longer, as it happened to be a 

 considerable time before he got another spark that communicated no sensible elec- 

 tricity. Dr. P. cannot help taking notice, that if it'had happened, that in his 

 first experiment the insulated tube had always acquired or lost the least sensible 

 electricity (and as he afterwards found, there were many chances against the first 

 result), he should have formed, and have acquiesced in, some sort of hypothesis, 

 to account for the giving or receiving of electricity in those circumstances, and 

 there the business would have ended; but the seeming contrariety of these ap- 

 pearances obliged him to pursue them further. 



Not being able completely to satisfy himself with his last conclusion, attended 

 with the difficulties above mentioned, he kept diversifying the experiments, and 

 introducing every circumstance that he could imagine might possibly affect the 

 result of them; and among the rest, he made the following experiments, which 

 quite unhinged him again, and left him as much at a loss as ever he had been 

 before. Having suspended a fine thread on an insulated brass rod, placed about 



