VOL. LXVIII.] PHILOSOPHICAL TRANSACTIONS. 333 



servants was out of doors by the coach-house at the same time, and narrowly 

 escaped falling by the strength of the flash : the others were in the house, but 

 were much frightened. My son says, that there is a dent in the cramp, on 

 which the lightning fell, and I intend to preserve it as a curiosity. If the con- 

 ductor on the house has acted, it is imperceptible as I am informed. I thought 

 this account would be acceptable to you from, honourable sir, &c. 



Edward Nickson. 



To the Right Hon. Lord Amherst, Lieut.-General of his Majesty s Ordnance, &c. 

 MT LORD, Office of Ordnance, Purfleet, May 20, 1777. 



In obedience to your lordship's commands of the igth instant, directing me 

 to report concerning the accident that happened to the Board's house by light- 

 ning on the 13th, I beg leave to acquaint your lordship, that on that day there 

 had been much rain and distant thunder ; but, about Q o'clock, in the afrernoon, 

 a very heavy cloud hung over the house for some time, which I looked at from 

 the back-parlour window, and it being quite calm, made me suspect that some 

 of our conductors might find employment from it. I had not been long at the 

 window before a violent flash of lightning and clap of thunder came together ; 

 and, as soon as the rain would permit any body to move about, one of the 

 labourers brought me some pieces of stone and a brick, which were struck off 

 from the copeing on the parapet-wall of the building from the north-east corner. 

 On my son's coming home, I desired him to go and view the top of the house. 

 On his return he told me, that the lightning had struck one of the cramps that 

 hold the copeing together, and had made a dent in the lead of the cramp, and 

 the stone adjoining to it, as if struck by a musket-ball ; that the quantity of 

 stone thrown down might amount to about a square foot ; and that it had dis- 

 turbed about a cube foot of brick-work underneath : and, according to your 

 lordship's commands, the distance from the point of the conductor on the house 

 to the part struck has been measured by him this day, and amounts to 46 feet. 

 All the conductors at this place are pointed, and it has not yet been discovered 

 that any of them have acted on this occasion. If your lordship should want any 

 farther explanation, my son waits on you with a small drawing of the elevation 

 of the east front of the house, and of the part struck, which I hope will be 

 satisfactory to your lordship and to the honourable board. I am, See. 



Edward Nickson. 



1. The Report of the Comviiltee appointed by the Royal Society, for Examin- 

 ing the Effect of Lightning, May 15, 1777 , on the Parapet-wall of the House 

 of the Board of Ordnance, at Purfleet, in Essex. — The iron cramp on which 

 the lightning fell was cemented into the copeing stones on the parapet- wall, near 

 the north-east corner, with lead: and on that lead, at one end of the cramp, 

 there appeared to have been a small fusion; the end of the lead, and part of the 



