' [ 537 1 
The next trial of this machine was on board a' 
fmall failing vefiel, in company with Dr. Knight, and 
Mr. William Hutchinfon, an experienced lea man, and 
matter of a confiderable merchant-fhip. Our expe- 
dition was upon the river Thames, and fome leagues 
below the Nore. • The intention of the trial here 
was, to find, in general, how far it agreed with the 
log, and how it would behave in the fwell of the 
fea ; a comparifon with the rheafure of a real difiance 
being here impracticable, on account of the tides and 
currents. 
The method of trial was this: We fuffered the 
whole log-line to run out, being 357 feet between 
the firfi knot and the end. The perion, who hove the 
log, gave notice, at the extremes of this meafure, that 
the perfon, who attended the dial of the machine, 
might fiop the fpindle at the beginning and end ; 
while a third obferved, by a feconds- watch, the time 
taken up in running thefe 3 57 feet. By thefe means, 
we were enabled to afcertain the comparative velocity, 
wherewith w'e moved, and the number of turns of 
the plate at each trial, correfponding to 3 57 feet by 
the log ; which, if the machine and log were both ac- 
curate, ought to have been always the fame. The 
particulars of thefe experiments are contained in the 
following table. 
Yyy 
Turns 
