63a PHILOSOPHICAL TRANSACTIONS. [anNO 1755. 



thus driven out of them into the prime conductor, and they become negatively 

 electrized, and therefore repel each other. 



Keeping the tube in the same place with one hand, attempt to touch the 

 threads with the finger of the other hand, and they will recede from the finger. — 

 Because the finger being plunged into the atmosphere of the glass tube, as well 

 as the threads, part of its natural quantity is driven back through the hand and 

 body, by that atmosphere, and the finger becomes, as well as the threads, nega- 

 tively electrized, and so repels, and is repelled by them. To confirm this, hold 

 a slender light lock of cotton, 2 or 3 inches long, near a prime conductor, that 

 is electrified by a glass globe, or tube. You will see the cotton stretch itself out 

 towards the prime conductor. Attempt to touch it with the finger of the other 

 hand, and it will be repelled by the finger. Approach it with a positively charged 

 wire of a bottle, and it will fly to the wire. Bring near it a negatively charged 

 wire of a bottle, it will recede from that wire in the same manner, that it did 

 from the finger ; which demonstrates the finger to be negatively electrized, as 

 well as the lock of cotton so situated. 



LII. Extract of a Letter concerning Electricity, from Mr. B. Franklin to 

 Mons. Delibard, inclosed in a Letter to Mr. Peter Collinson, F. R. S. Dated 

 Philadelphia, June 29, 1755. p. 305. 



You desire my opinion of Pere Beccaria's Italian book. I have read it with 

 much pleasure, and think it one of the best pieces on the subject, that I have 

 seen in any language. Yet as to the article of water-spouts, I am not at present 

 of his sentiments ; though I must own with you, that he has handled it very 

 ingeniously. Mr. Collinson has my opinion of whirlwinds and waterspouts at 

 large, written some time since. I know not whether they will be published ; if 

 not, I well get them transcribed for your perusal. It does not appear to me, 

 that Pere Beccaria doubts of the absolute impermeability of glass in the sense I 

 mean it ; for the instances he gives of holes made through glass by the electric 

 stroke, are such as we have all experienced, and only show that the electric 

 fluid could not pass without making a hole. In the same manner we say, glass 

 is impermeable to water, and yet a stream from a fire-engine will force through 

 the strongest panes of a window. As to the eft'ect of points in drawing the elec- 

 tric matter from clouds, and thereby securing buildings, &c. which, you say, he 

 seems to doubt, I must own I think he only speaks modestly and judiciously. 

 I find I have been but partly understood in that matter. I have mentioned it in 

 several of my letters, and except once, alwavs in the alternative, viz. that pointed 

 rods erected on buildings, and communicating with the moist earth, would either 

 prevent a stroke, or, if not prevented, would conduct it, so as that the building 



