C 894 ] 
ground, perceived a motion under them, which they 
compared to the beating of the pulfe. They men- 
tion like wile, that after this motion ceafed to be felt, 
there was perceived another, which they compare to 
that felt in a boat on a river, the current of which 
is very flow. Thofe only, who lay on the ground, 
were fenfible of this motion ; for fuch, as were fitting 
on chairs, or {landing, perceived nothing of it. 
This is the whole, Sir, of what I have learned on 
this fubjeft. I leave you to judge, whether it be worth 
communicating to the Royal Society ; whom I re- 
quefl: you to allure of my moll profound refpe£t, and 
of my deflre to merit the honour done me of admit- 
ting me into their body. 
I am with the greateil regard, 
Sir, 
Your mod humble 
and moll obedient fervant, 
A. Trembley* 
CXVI. A*. 
