VOL. LIV.] PHILOSOPHICAL TRANSACTIONS, ] 27 



was in this wooden frame, is torn from the frame on the two sides of it next the 

 holdfast, and is rent besides in several places. ' i 



The whole appearance of the damage done to this church very much favours 

 the conjecture of Dr. Franklin, who thinks it probable, that by means of metallic 

 rods or wires, reaching from the roofs to the ground, any buildings may be se- 

 cured from the terrible effects of lightning. 



XL. Observations on the Effects of Lightning, with an Account of the Appara- 

 tus proposed to prevent its Mischiefs to Buildings, more particularly to Powder- 

 Magaziries; being Answers to certain Questions proposed by M. Calandrini, 

 of Geneva, to fVm. Watson, M.D., F.R.a. p. 201. 



M. Calandrini's questions are as follow: 1. What sort of apparatus is used 

 at Philadelphia? 2. Whether there is not some improvement to be made to their 

 methods; 3. In what manner this apparatus may be adapted to powder maga- 

 zines? 4. Into what place the thunder may be conducted, where there is no 

 river near, to answer the purpose of the sea about ships? 5. Whether the appa- 

 ratus might not electrify the air, so as to occasion lightning, which was, he 

 believes, the cause of the death of professor Richmann of Petersburg? This ap- 

 paratus may not be dangerous to dwelling houses, where the fire may slip with- 

 out any manner of risk; but may be attended with the most dreadful conse- 

 quences to a powder magazine, where the smallest spark may occasion the 

 explosion of the whole. 6. Whether the square, or the circular form of build- 

 ing, will be easiest adapted to the apparatus ? 7. Whether an iron bar fixed on 

 the top of the building, to support a weather-cock, may not attract the thun- 

 der-bolt, and be consequently dangerous to all buildings; but more especially to 

 powder-magazines ? Whether there is not some particular manner of buildings, 

 invented of late, adapted to powder magazines; either to diminish the shock of 

 the explosion, or to secure them against any accident, by the methods used at 

 Philadelphia. 



M. Calandrini says further, that he himself has been eye witness of the effects 

 of lightning coming into a room, which had received much damage from it. 

 That he looked for the place it went out at, and after long search perceived that 

 it had followed the wire of the bell, which had conducted it through a very in- 

 considerable hole into the next room ; whence it bad opened itself a passage into 

 a back yard. This accident was at that time thought \&ry extraordinary, being 

 anterior to Dr. Franklin's experiment. 



To M. Calandrini's questions Dr. W. sent the following answers : 



1. The apparatus used at Philadelphia consists either of a long iron rod, placed 

 on the highest part of a house or other building; or of a shorter rod, inserted 

 into a long wooden pole, placed in the same manner. The iron rod, mentioned 



