OBSERVATIONS WITH THE HORIZONTAL NEEDLE.
May,
Aug.
July,
July,
Nov.
Feb.
April
Mav,
Oct.
Apr.
Feb.
Dec.
July,
1825
1826
1827
1825.
Portsmouth,
N.W; Coast of America,
Chamisso Island,
Petropaulski *,
San Francisco,
Woahoo,
Macao,
Loo Choo,
iTalcahuana,
1826. Otaheite,
Bow Island,
1825. Pitcairn Island,
Rio Janeiro t , •
Aug. 1827. Chamisso Island,
July,
Dec.
’etropi
San Fr
laulski.
May, 1828. Coquimbo,
50 47;
70 31
66 n
53 01
37 48 21 18
22 09
26 12
36 421
17 30
18 06
25 04
22 54
the Nee
66 12n
53 01
37 48
29 57
Longitude.
Temperature.
160 30
161 46
201 16
122 23
158 00
146 28
J32 18
73 00
149 32
140 61
130 08
43 05
die was
161 46w
201 16
22 23
71 17
56
67
57
49
67
80
77
71
61
81
83
75
72
remag
56
40
53
64
Mean T ime, 100 \'ib .
Observed. Computed.
S.
497.5
682,1
600.12
456.4
422,67
390.36
373.3
376.6
3673
357.0
354.4
354.1
371.9
594.
440.4
422.9
S.
600.10
455.06
444.7
396.25
387.73
391.47
Standard.
450.36
440.18
387.12
Observed. | Computed.
1.00
1.1565
1.0866
.9178
.9986
.7233
.6934
.96522
.9954
.7302
1.00
1.1190
1.0868
.9234
.9860
.7014
,6426
• Observed by Mr. YVolfe (mid.).
t Assuming the Dip to be 14’ 23' 6 '' S., according to Captain King’s observations.
TABLE XII.
VARIATION OF THE COMPASS.
T h e first p a rt o f th is T a b le contains th e results o f observations made a t sea with G ilb e rt’s
compass, an d with Barlow’s plate attached. I m ig h t have added anothe r column o f results
with th e plate detached, as o u r observations were always made w ith and without th e p l a t e ;
b u t this would have lengthened th e table perhaps unnecessarily. T h a t useful invention of
M r. Barlow for neutra liz ing th e effect o f th e ship’s iron upon the compass cannot be too
highly extolled, and every ship o u g h t to be provided with it. Afte r th e Biossom h a d every
th in g on board, the local deviation o f the needle was ascertained b y swinging th e ship a t
Spithead, and th e position o f the plate determined b y tb e directions which accompanied the
platel A strong stand was th en made and fitted into wooden shoes nailed to th e deck ; after
which all the observations were taken precisely in th e same place. I n 1827 it became necessary
to a lte r th e position o f th e p la te a little , on account o f a different distribution o f tb e iron
in th e ship. T h is was done p u rsu a n t to experiment made a t Petropaulski.
T h e second p a rt o f this table contains the variation o f the compass from observations made
on shore, a t different p a rts o f th e globe, principally with two o f Ka te r’s compasses, Nos. I
and 2, th e errors o f w hich were —8« 58 ' and —2« 18' respectively. In tb e table these errors
have been allowed.
I have given tb e re su lt o f my observations in various p a rts o f Kotzebue Sound separately,
in order to show th a t th e local disturbances on shore, o f which Cap tain Kotzebue speaks
in his narrative, vol. i. pages 214 and 220, did not exist a t th e period o f o u r visit. T h a t
officer informs us th a t th e disturbance a t E lep h a n t Po in t occasioned an error o f 4 3 “ ! and at
Chamisso Island o f 31«; and th a t he was a t length obliged to resort to his vessel for correct
results. In tbe annexed table it will be seen th a t whatever mig h t have been the cause o f the
above mentioned error in tlie variation in 1816, it was suspended in 1826 and 1827, as the
observations did not differ more th an mig h t be expected in a high magnetical latitude, and
from their being made with different instruments.
In the first p a rt of the table all th e observations were made b y myself; similar results
were obtained by Lieutenant Belcher, YVainwright, and b y otlier officers o f th e ship, wliich I
have omitted here, to avoid repetition. In th e second p a rt, as th e observations are fewer and
more interesting, I have given the results o f th e o th e r officers with my own, and di.stinguished
each with th e in itial o f the o b serv er; Bk, L ieu ten a n t Bclclicr; YV., L ieu ten a n t YY^ainwright;
B., Captain Beechey.