342 
ME. WAEEEN DE LA EUE ON THE 
The pocket chronometer, Frodsham No. 9768, was found to have the following rates 
and errors; — 
sec. 
From June 26 to June 29. its daily rate was losing 1-05 
From June 29 to June 30, its daily rate was losing 2-84 
From June 30 to July 3, its daily rate was losing 2'00 
h 
On June 26, 15, it was slow of Greenwich mean time . . . . 3-0 
On July 3, 15, it was slow of Greenwich mean time 15*0 
From these data, the mean daily rate was 1*71 seconds losing. On the 17th or 18th 
of July this chronometer tripped, most likely in consequence of its having been touched 
by the inmates of my lodgings ; and it was therefore useless to make any determination 
of its error on my return from Spain. 
From a comparison with the box chronometer to be next mentioned, for the loan of 
which I was indebted to the kindness of Mr. Feodsham, I estimated the error on Green- 
wich mean time of Frodsham 9768 to be 3*2 sec. slow, for July 3, 15^, instead of 3 sec., 
as found by observation. The comparison was made on June 25, 22** : two hours later 
Mr. Ellis found the box chronometer, Frodsham sec. 
No. 3094, to be on June 26, O** 1*9 slow of Greenwich mean time. 
In two hours 3094 would have gained .... 0*08 
At the time of comparison 9768 was slow of 3094 0*50 
Between the comparison and the ascertaining of 
the error of 9768, namely 17 hours, the latter 
would lose 0*74 
Estimated error of Frodsham 9768, on June 26, 15^ 3*22 
This .difference between 3*2 sec. and 3*0 sec. might have been occasioned by the 
journey of No. 3094 to Greenwich, but in any case was so small that, for the subsequent 
calculations, I retained without correction the error afterwards determined by observa- 
tion on July 3, 15'*, when Frodsham 9768 was slow of Greenwich mean time 15*0 sec.; 
whence on July 5, 0^, its error would have been 17*3 sec. slow of Greenwich mean time. 
The box chronometer, Frodsham No. 3094, was (through the kindness of the Astro- 
nonomer Eoyal) compared at Greenwich by Mr. Ellis, whose determination of its errors 
are given below. 
h 
m 
sec. 
June 26 . 
. . 0 
0 
1*91 
June 27 . 
. . 0 
0 
1*0 
^slow of Greenwich mean time. 
June 28 
. . 0 
0 
0*5^ 
June 29 
. . 0 
0 
1*3'' 
.June 30 
. . 0 
0 
2*3 
July 1 . 
. . 0 
0 
■ fast of Greenmch mean time. 
July 2 . 
. . 0 
0 
3*6 
July 3 . 
. . 0 
0 
4*5, 
