S4S On the Diurnal Variation of the Needk, 
public, a favourite speculation amongst our merchants. The 
oil procured from the sea-lion is, I am told, nearly equal in value 
to that of the spermaceti whale. And the great number of 
whales we saw every where near the land, must also bo an im- 
portant thing to our merchants, as they have lately been said to 
be very scarce to the northward. 
We left the coast on the st of March, and arrived at this 
place on the 14th of April, having touched at Juan Fernandes 
for refreshment. 
H. M. S. Slaney, 1 
V ALP AE Also, May 1820. ) 
Aet. XVIII. — Observations on the Diurnal Variation of the 
Needle from 1775 to 1780, at Zwanenhurg in Holland. 
The following very valuable table of the diurnal variation of 
the magnetic needle, at Zwanenburg in Holland, has been 
obligingly communicated to me by Colonel Beaufoy, who received 
it from our learned correspondent Mr Charles Bumker, Direct 
tor of the Nautical Academy of Hamburgh. We are not ac^ 
quainted either" with the name of the observer, or with the nature 
of the apparatus by which the variation was determined ; but we 
shall be able, in a subsequent Number, to comipunic^te this in-, 
formation to our readers. D. B. 
Year. 
Jan. 
Feb. 
Mar. 
April. 
May. 
June. 
July. 
Aug. 
Sept. 
Oct. 
Nov. 
Dec. 
1775, 
O 
o 
Morn. 
21°39 
21°38 
2r29 
21°33 
1776, 
2i!38 
2L36 
2L38 
22.3 
22.3 
22°.0 
22J 
2L57 
21.28 
21.17 
21.9 
21.40 
1777, 
21.37 
21.48 
21.45 
21.51 
21.49 
22.19 
21.54 
22.6 
22.30 
22.40 
22.18 
21.54 
1778, 
22.1 
21.45 
21.48 
21.54 
22.17 
23.2 
23.2 
22.59 
23.4 
22.53 
22.32 
22.40 
1779, 
22.42 
22.11 
22.14 
22.47 
22.39 
22.35 
22.34 
22.42 
22.39 
22.42 
22.42 
22.41 
1780, 
22.33 
22.31 
22.33 
22.37 
22.32 
22,33 
22.33 
22.24 
22.33 
22.35 
22,37 
22.36 
1775, 
1776, 
21.39 
21.37 
21.47 
22.12 
22.9 
Noon. 
22.5 
22.6 
22.6 
21.43 
21.38 
21.43 
21.24 
21.30 
21.18 
21.37 
21.44 
1777, 
21.41 
21.54 
21.50 
21.54 
21.53 
22.23 
21.57 
22.11 
22.32 
22.41 
22.19 
21.58 
1778, 
22.3 
21.47 
21.50 
21.58 
22.20 
23:2 
2 S .3 
23.00 
23.5 
22.53 
22.33 
22.37 
1779, 
22.46 
23.13 
23.13 
22.49 
^2.39 
22.35 
22.35 
22.43 
22.40 
22.43 
22.43 
22.40 
1780, 
22.33 
22.32 
22.35 
22.37 
22.32 
22.34 
22.34 
22.24 
22.34 
22.36 
22.38 
22.37 
1775, 
1776, 
21.37 
21.35 
21.40 
22.6 
22.8 
Even. 
22.4 
22.3 
22.1 
21.39 
21.32 
21.41 
21.19 
21.27 
21.10 
21.35 
21.42 
1777, 
21.38 
21.47 
21.44 
21.52 
21.50 
22.41 
21.55 
‘22.10 
22.30 
22.38 
22.17 
21.56 
1778, 
22.00 
21.45 
21.47 
21.55 
22.19 
2^.0 
23.1 
22.59 
22.51 
23.3 
22.32 22.36 
1779, 
22.45 
23.12 
23.11 22.48 
22.38 
22.34 
22.33 
22.41 
22.39 
22.42 
22.42 22.39 
1780, 
22.31 
22.30 
22.34| 
22.37| 22.32 
22.34 
22.33/ 
22.23 
22.33 
22.34 
22.36 22.35 
