VARIATION OF THE COMPASS. 
735 
TABLE XII. 
VARIATION OF THE COMPASS. 
The first part of this Table contains the results of observations made at sea with Gilbert’s 
compass, and with Barlow’s plate attached. I might have added another column of results 
with the plate detached, as our observations were always made with and without the plate ; 
but this would have lengthened the table perhaps unnecessarily. That useful invention of 
Mr. Barlow for neutralizing the effect of the ship’s iron upon the compass cannot be too 
highly extolled, and every ship ought to be provided with it. After the Blossom had every 
thing on boai'd, the local deviation of the needle was ascertained by swinging the ship at 
Spithead, and the position of the plate determined by the directions which accompanied the 
plate. A strong stand was then made and fitted into wooden shoes nailed to the deck ; after 
which all the obsei'vations were taken precisely in the same place. In 1827 it became neces- 
sary to alter the position of the plate a little, on account of a different distribution of the iron 
in the ship. This was done pursuant to experiment made at Petropaulski. 
The second part of this table contains the variation of the compass from observations made 
on shore, at different parts of the globe, principally with two of Rater’s compasses. Nos. 1 
and 2, the errors of which were — 8® 58* and — 2° 18* respectively. In the table these errors 
have been allowed. 
I have given the result of my observations in various parts of Kotzebue Sound separately, 
in order to show that the local disturbances on shore, of which Captain Kotzebue speaks 
in his narrative, vol. i. pages 2141 and 220, did not exist at the period of our visit. That 
officer informs us that the disturbance at Elephant Point occasioned an error of dS"! and at 
Chamisso Island of 31° ; and that he was at length obliged to resort to his vessel for correct 
results. In the annexed table it will be seen that whatever might have been the cause of the 
above mentioned error in the variation in 1816, it was suspended in 1826 and 1827, as the 
observations did not differ more than might be expected in a high magnetical latitude, and 
from their being made with different instruments. 
In the first part of the table all the observations were made by myself ; similar results 
were obtained by Lieutenant Belcher, Wainwright, and by other officers of the ship, which I 
have omitted here, to avoid repetition. In the second part, as the observations are fewer and 
more interesting, I have given the results of the other officers with my own, and distinguished 
each with the initial of the observer; B^, Lieutenant Belcher ; W., Lieutenant Wainwright; 
B., Captain Beechey. 
