C 379 ] 
ExtraSi 0 / L E T T E R XVI.' 
From Swanzey, dated Decem. 8, Communi- 
cated by the Rev. John Blair, LL.D. F. R. S. 
Read Jan. 8, the firft of November, about two 
*75 • hours ebb of the tide, and between 
fix and feven a clock in the evening, at a place called 
White-rock, about a mile up this river, where great 
numbers of fhips load coal, and difcharge copper- 
ore, for the ufe of the works eredted at that place, 
a great head of water rufhed up with a great noife, 
floated two large veflels, the leafi; above two hundred 
tons (one whereof was almoft dry before), broke 
their moorings, arid hove them acrofs the river, and 
had like to overfet them, by throwing them on the 
banks. The whole did not laft ten minutes, the rife 
and fall j and, what is moft remarkable, it was not 
felt in any other part of the river j fo that it mufi: 
have guihed out of tlie earth at that place ; for near 
the town and mouth of the river there is a paflage- 
boat, that was paffing at that time, arid had been for 
the whole day, it being our market-day, when that 
boat is constantly employed', and there nothing was 
felt of it. This is the befi: account I can get, and 
what is/faid to‘be matter of fa^l. 
6 c c a 
Extrabi 
