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M. Calandrini fays further, that he liimfelf has 
been eye-witnefs of the effe&s 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 fearch perceived that it had followed the 
wire of the bell, which had conduced it through 
a very inconfiderable hole into the next room j from 
whence it had opened itfelf a pafiage into a back yard., 
Thisaccident was at that time thought very extraordi- 
nary, being anterior to Dr. Franklin’s experiment. 
To M. Calandrini’s questions I have fent the fol- 
lowing anfwers, 
I. The apparatus, ufed at Philadelphia, confifb 
either of a long iron rod, placed upon the highefl 
part of an houfe, or other building ; or, of a fhorter 
rod, inferred into a long wooden pde, placed in the 
fame manner. The iron rod, mentioned by Mr. 
Kinnerfley in the Philofophical * Tranfa&ions, and 
which probably preferved the houfe in Philadelphia 
upon which it was placed, extended in height about 
nine feet and a half above a ftack of chimnies, to 
which it was fixed 5 but he fuppofes that three or 
four would have been fufficient. Tbefe rods are 
pointed at their upper extremity. It is indifferent, 
which of thefe two are ufed, provided that they 
are of height enough to reach above the chimnies, 
or any other part of the edifice. Connedled to, or 
fufpended from, the metal of thefe, a metallic wire, 
generally of iron, is conduced, in the eafieft and 
moft convenient manner, to the neareft water, viz. 
£0 the well of the houfe, or any other water in the 
neighbourhood. 
* Vol. LI II. page 95, 
D d 2 II. This 
