54 Prof. Thomson on some remarkable effects of Lightning. 



house in my immediate neighbourhood. I called shortly 

 afterwards and brought away the wires and the paper which 

 I enclose. * * 



" I have some difficulty in accounting for the appearance of 

 the wires. You will observe that they have been partially fused ; 

 and when I got them first, they adhered closely to one another. 

 You will find that the flat sides exactly fit. They were both 

 attached to one crank, and ran parallel to one another. The 

 question is, how were they attracted so powerfully as to be 

 compressed together? * * 



" You will observe that the paper is discoloured. This 

 has been done, not by scorching, but by having some sub- 

 stance deposited on it. There was painted wood also dis- 

 coloured, on which the stratum was much thicker. It could 

 easily be rubbed off, when you saw the paint quite fresh be- 

 neath. * * 



" The farmer showed me a probang which hung on a 

 nail. The handle only was left. The rest, consisting of a 

 twisted cane, had entirely disappeared. By minute examina- 

 tion I found a small fragment which was not burnt but broken 

 off." 



[The copper wires, and the stained paper enclosed with 

 Mr. Leitch's letter, were laid before the Society.] 



The remarkable effects of lightning described by Mr. 

 Leitch, are all extremely interesting. Those with reference 

 to the copper wires are quite out of the common class of 

 electrical phenomena; nothing of the kind having, so far as 

 I am aware, been observed previously, either as resulting 

 from natural discharges, or in experiments on electricity. It 

 is not improbable that they are due to the electro-magnetic 

 attraction which must have subsisted between the two wires 

 during the discharge, it being a well-known fact that adja- 

 cent wires, with currents of electricity in similar directions 

 along them, attract one another. It may certainly be doubted 

 whether the inappreciably short time occupied by the elec- 

 trical discharge could have been sufficient to allow the wires, 

 after having been drawn into contact, to be pressed with 

 sufficient force to make them adhere together and to produce 

 the remarkable impressions which they still retain. On the 

 other hand, the electro-magnetic force must have been very 

 considerable, since the currents in the wires were strong 

 enough nearly to melt them; and, since they appear to have 

 been softened, if not partially fused, the flattening and re- 

 markable impressions might readily have been produced by 

 even a slight force subsisting after the wires came in contact. 



