126 PHILOSOPHICAL TRAKSACTION9. [aNNO 1764. 



rated solids, the sides of which are continually divided in the same ratio by the 

 points of contact; these two solids will be equal. 



And the same of solids in like manner described between conjugate hyperbolas. 



Many other similar properties of conic sections will easily appear. 



And such properties may be affirmed of infinite other curves, as may easily be 

 deduced from the Micell. Anal. 



XXXFI. On the Ejects of Lightning at South Weald in Essex. By TV. He- 



berden, M.D., F.R.S. p. 198. 



On Monday June 18th, 1764, between 12 and 1, about 3 hours before the 

 time when the thunder and lightning happened in London, by which St. Bride's 

 steeple and Essex-street were damaged, there was a storm at South Weald, at- 

 tended with uncommonly loud thunder. The lightning struck the weather-cock, 

 and passing along the iron bars, on which it stands, rushed against the walls of 

 the turret, and broke a space from the top of the turret to the leads of the tower, 

 about 4 feet wide, being about one-third of the circumference of the turret and 

 facing the north. The weather-cock and irons that support it were unhurt. 

 The walls of the turret were made of rough stones and mortar: and part of what 

 was beaten down fell on the leads of the tower underneath, and part on the roof 

 of the church, which was greatly damaged. The stair-case also, which leads up 

 to the turret, was so full of the stones and mortar, that it was with great diffi- 

 culty and some hazard that any one could go up it. From a leaden spout at this 

 west end of the church, which only comes down to near the top of the west 

 window, the plaster was beaten off the wall for some inches in breadth quite to 

 the window; and at the bottom of the upright iron bars of this window several 

 of the stones were cracked, and the wall chipped here and there from thence to 

 the ground. The same is observable in the stones at the bottom of the upright 

 iron bars in the east window, which was also near a leaden spout that comes 

 down from the roof over the chancel, the end of which rests on a buttress, and 

 does not reach the ground by several feet ; which buttress is cracked, as well as 

 the adjoining wall. On the inside of this wall, within the church, there is a 

 large wooden frame, which holds the commandments. This frame at the left 

 hand corner is supported by an iron holdfast driven into the wall, which was 

 mentioned above as being cracked on the outside under the leaden spout. The 

 blaster of the wall, for 3 or 4 inches all round this holdfast, within the church, 

 is beaten off; and to the left hand there is a space, slanting from the holdfast to- 

 ward the ground, 5 or 6 inches wide and 3 or 4 feet long, from which all the 

 mortar is forced away. That part of the wooden frame wh'ere the holdfa^it is 

 fixed is shattered. The canvas, on which the commandments are painted, which 



