VOL. LIX.] PHILOSOPHICAL TRANSACTIONS. 623 



the metallic communication is complete to the lower end of the pipes^. that dis- 

 charge the water from the circular part of the great cupola, on the floor of the 

 stone gallery. 



From the bottoms of these pipes, which terminate with a shoe of lead within 

 half a foot of the floor of the stone gallery, the metallic communication is again 

 interrupted to the top of the leaden pipes, which convey the water from thence. 

 Here it is proposed that conductors of lead, not less than 4 inches in breadth and 

 half an inch in thickness, should be placed so as to be in contact with the bottom 

 of 4 of the pipes that come from above, and with the top of 4 of those that 

 descend. Lead is recommended to be employed here, as more readily adapting 

 itself to the various curvatures it must meet with in the now proposed ar- 

 rangement. 



These last pipes, after descending below the colonnade, near the circular stair- 

 cases, make their appearance on the outside of the drum-part of the cupola; 

 where they are bent at obtuse angles, and discharge their water upon the roof of 

 the church. From these angles to the roof the distance is about 5 feet. Here 

 then is another interruption to the metallic communication. This is proposed to 

 be completed by conductors of lead similar to those before mentioned, which 

 should be so placed as to be in contact both with the bottom of the pipes and 

 the adjoining roof. 



From the roof, as has already been mentioned, the leaden pipes are continued 

 below the surface of the earth, and terminate in a drain; and thus, by the me- 

 thod now directed, the metallic communication will be completed from the cross 

 on the top of St. Paul's church to some feet below the surface of the ground. 



The committee then turned their thoughts towards the two towers at the west 

 end of the church; and here they beg leave to observe, that in one of these 

 towers, between the pine apple and the leaden bell-shaped covering near it, placed 

 at the top of each of these towers, there is no metallic communication deserving 

 notice, till you come to the lead on the roof of the church. This distance is 88 

 feet. To this tower therefore it is proposed to adapt a rod or bar of iron, not 

 less than an inch and a quarter square, in such a manner, that one end of the 

 bar should be in contact with the metal communicating with the pine apple on 

 its top, which is of copper, and the other end with the lead on the roof of the 

 church. 



In the middle of the other tower, in which the great bell is hung, there is an 

 iron stair-case of considerable height, which is placed in the middle of it, for the 

 more conveniently coming at the clock-work. The top of this stair-case is at no 

 great distance from the leaden covering on the top of the tower : but from the 

 bottom of this stair-case to the roof of the church, between which there is no 

 metallic communication, the distance is considerable, not less than 40 feet. 



