[ 66 5 ] 
were fome others no lefs violent, in my opinion, but 
of much lefs duration. 
In general they were felt more fenfibly in the up- 
per rooms than on the ground-door ; and Ids by 
thofe, who were then walking either in the city or 
country, and not at all by many. The motion was 
hkewife different, mod; commonly, according to the 
quarters of the city, and was not the greatdl in the 
higheft parts of it. 
All the fhocks were not of the fame kind. The 
motion was undulatory in thofe of the 26th of De- 
cember, and 1 8th of February ; but the undulations 
on the former of thefe days were longer than, thofe 
on the latter. 
At other times there were obferved only a riling 
and linking again ; and mod; commonly a lhaking 
on one fide. I had fufpended a weight over my 
billiard-table fome lines above the carpet ; and I had 
furrounded it with billiard balls. I defigned to re- 
mark by this contrivance the direction, and, to a 
certain point, the degree of the force: but my balls 
did not move ; nor did I make the experiment till 
after the great fhocks were palfed. With the fame 
view Monf. Hofman had exaftly filled with water a 
large vefiel, which he had powdered all round : but 
he undertook this method as late as I did mine. Once 
only fome drops of water fell from the vefiel. A 
good number of people pretended to have obferved 
the direction ; but, in my opinion, there was none 
l'enfible to us. 
During the mod violent lhakings there were fome 
kind of fialhes of lightning. The whole was pre- 
ceded by a groaning under-ground, which, when the 
fhocks 
