VOL. LXIV.] PHILOSOPHICAL TRANSACTIONS. 517 



in it. I repeated the experiments many times, and always with the very same 

 result. 



Mr. H. then relates an experiment by Tho. Ronayne, Esq., to the same 

 effect, whence this gentleman draws the following inference: " Now as bodies 

 act at a greater distance, by how much they are more acute, and thereby diminish 

 any known electrical force; and, as in any particular case, the smaliness of the 

 pencil, or stroke, depends on the acuteness of the point presented, I cannot 

 avoid giving my suffrage for points, in preference to obtuse bodies." 



It may not, says Mr. H., be improper to introduce, in this place, an experi- 

 ment lately made by Mr. Edward Nairne, in Cornhill; which, though it does 

 not immediately relate to the particular subject of this paper, is a very proper 

 one to demonstrate the utility of metallic conductors in general. 



Mr. Nairne s Experiment. — He affixes, in a little apparatus, resembling the 

 hulk of a ship, a glass tube, about 8 inches long, and half an inch in diameter, 

 to represent the main-mast. The ends of the tube, which is filled with water, 

 are properly secured by corks; and through each cork a wire is introduced, of 

 such a length as to reach nearly to the middle of the tube, and leave a distance 

 of about half an inch, between the ends of the two: as in a curious experiment 

 of Mr. Lane's, made with small phials. A slight shock, discharged through 

 this apparatus, instantly breaks the tube in pieces, at that part, where the elec- 

 tric matter quits the upper wire, and expands itself in the water, before it reaches 

 the lower one; as the natural electiicity has been observed to do in bodies 

 wherein it has met with such an interrupted and broken communication of me- 

 tal; but Mr. Nairne having fixed, at the top of such a glass tube, and united 

 with the wire of it, a piece of very small harpsichord wire, which was continued 

 to the bottom of it, and there fastened to a regular communication of metal, 

 in contact with the coating of the jars; he discharged through it his 4 batteries 

 united, consisting of 64 jars, containing 50 square feet of coated surface fully 

 charged, when the whole of the small wire was instantly exploded and lost; but 

 the tube remained unhurt: An effect analogous to that of the natural electricity,' 

 where, though it has sometimes happened that the conductor, being too small, 

 has been in part destroyed, or much injured by a stroke; yet the building, to 

 which such a conductor has been affixed, has escaped, without receiving the least 

 damage. '^ 



Among some very interesting remarks on the effects of lightning, by Pro- 

 fessor Winthrop of New Cambridge, which have- lately been communicated to 

 me by Dr. Franklin, I find one, on the influence of sharp pointed conductors, so 

 immediately relating to the question under consideration, that no apology will be 

 necessary for introducing it in this place. Dr. Winthrop having given a very • 

 curious and exact account of a violent flash of lightning, which fell on and 



