Profefor WILLIAMS on Earthquakes. 271 
preceded with a very loud report ; and is faid to have rofe to 
fuch a violence, as to fhake down fome bricks from the tops of 
. fome chimnies, and alfo fome pieces of ftone wall. The cour fe 
of this earthquake is faid, by fome that remember it, to have 
been from the weffward to the eaffward. As to other particu~ 
lars I can find no account.+ 
"The next earthquake, that fhook the whole country, was in 
the year 1755. November 18, N. S. at 4* 11! 35",t ina 
calm, ferene and pleafant night, came on the moft violent fhock 
of an earthquake that was ever known in New-England. The 
firft thing obfervable, was that rumbling noife, or roar, which 
as a found fui generis, feemed a prelude to an earthquake. In 
about half a minute, the furface of the earth feemed to be fud- 
denly raifed up ; and, in fubfiding, was thrown into a univer- 
fal trembling, ora very quick, jarring, vibratory motion, which 
acted in an horizontal direction. ‘This motion continued for. 
about a quarter of a minute, and then abated for three or four 
feconds. Then, all at once, came on a violent, prodigious 
thock, "as ‘fuddenly, to appearance, as a thunder-clap breaking: 
| nid n upon 
E Phil L Tras fr 17 Ba pae Lii vinos: jae e tl 
$ The beginning of this earthquake was determined to all the exa&nefs that could 
be defired, by the following accident.—Profeflor Winthrop at Cambridge, fome time 
before, having ufed a pretty long glafs tube, in a particular experiment,, fhut it up? 
in his clock-cafe, for fecurity. ` This tube, ftanding nearly perpendicular, muft have. 
been overftt by the firft fhock, which made it impoffible for the pendulum to make | 
any ofcillation, after the tube had ftruck againft it. „ The clock ftopped at the time’ 
mentioned above. Being a very good one, and having been adjufted by a meridian. 
line, the preceding noon, it muft have pointed out the beginning of the earthquake. 
te a great precifion. Had the time. been as accurately determined at any othig 
diftant place, the on of its motion might have been determined to great exact: 
nefs. 
