816 Dr. mu s grave’s Reafons for diffenting 
completed the circuit. After the explofion the diftances 
were meafured. In the experiments which I faw the 
phenomena were as follows : in the firft, the diftance of 
the ball was 41 of an inch, that of the point in 
the fecond, diftance of the ball —, of the point in 
the thhd, diftance of the ball of the point |4? in the 
fourth, diftance of the ball of the point In all 
thefe experiments the point, though con fider ably farther 
off from the coating of the phial, was ftruck in pre- 
ference to the ball. In a fifth experiment, when the 
point flood at double the diftance, the ball was ftruck, 
and not the point. 
'The refult of thefe experiments being fo widely dif- 
ferent from the refult of that made by Mr. henly, is a 
clear proof that he formed his conclufions too haftily, 
having attributed to fharpnefs and bluntnefs a pheno- 
menon caufed by the unequal refinances of the chains. 
As this experiment may be made with almoft: any -ma- 
chine, thofe who do not chufe to repeat it will have no 
right to plead the want of a fufficient apparatus, and 
muft look out for fonae other reafon to evade the force 
of it. 
I come now to confider more particularly the practical 
queftion, whether the fharp-pointed or the blunt con- 
ductors are moft proper to be affixed to buildings, as 
prefervatives 
