1 66 Captain Sabine's experiments to determine the 
on the Island of Brassa. It happened unfortunately, that in 
the interval between the 30th of April and the 3d of May, 
on which morning the clocks were re-embarked to proceed on 
the voyage, the state of the weather was such as to prevent 
the use of the transit instrument. The rate of the clock was 
therefore ascertained at this station by comparison with a 
chronometer, the accuracy of the result being of course de- 
pendent on the steadiness with which the chronometer main- 
tained its accustomed rate. No. 1024, of Earnshaw, selected 
on this occasion, had been received on board on the 15th of 
April, with an assigned rate of gaining one second daily, 
founded on a trial of several weeks. The longitude of Brassa 
is not ascertained with sufficient correctness to determine, by 
a knowledge of the error of the watch on mean time whilst 
there, the rate since the 15th ; but on the 9th of June, being 
the first good opportunity of lunar observation which oc- 
curred subsequently, the Greenwich time obtained by the 
mean of several sets of distances taken by different observers, 
and with different instruments, agreed within four seconds of 
that shown by 1024, with its rate for the interval of 56 days 
applied. It may be also stated, as affording an inference 
that the rate had been particularly maintained during the 
early part of this interval, that a second chronometer of Mr. 
Earnshaw’s, No. 815, had been sent on board, also on the 
15th of April, with a rate gaining o ",54 daily* determined by 
a similar trial to No. 1024; on the 1st of May 1024 had 
gained on 815 since the 15th of April 6,3 seconds, being 
only 6 - tenths of a second less than the difference of their 
respective rates. 
The latitude of Mr. Mouatt’s house 6o° 09' 42" N. was 
