MAJOR SABINE ON TERRESTRIAL MAGNETISM. 
131 
Weights. 
July 6th, 1838. 
June 24th, 1839. 
Angle of de- 
flection. 
Angle of de- 
flection. 
Corrected angle. 
grains. 
Therm. 67°. 
Therm. 59°. 
Therm. 67°. 
0-8 
29 58 
29 58 
30 02 
0-9 
34 16 
34 16 
34 20 
1*0 
38 47 
38 33 
38 37 
M 
43 33 
43 39 
43 43 
1-2 
48 32 
48 52 
48 56 
And this conclusion is further corroborated by the following observations made with 
the same needle at Rio de Janeiro in September 1838, and April 1839. 
Weights. 
September 4th 1838. 
April 4th, 1839. 
Angle of de- 
flection. 
Corrected angle. 
Angle of de- 
flection. 
Corrected angle. 
grains. 
Therm. 76°. 
O / 
Therm. 67°. 
o / 
Therm. 83°. 
o / 
Therm. 67°. 
o / 
0-8 
53 35 
53 30 
53 41 
53 31 
0-9 
65 12 
65 07 
65 25 
65 15 
When used on board ship the instrument was placed on a stand fitted with gimbals 
situated about the middle of the upper deck, and the same position was preserved in 
each of the three vessels. On a few occasions in the Arrow, the weather being very 
unfavourable, the observations were made in the cabin ; these results are distinguished 
in the Table by a mark, signifying that they are entitled to less confidence than the 
others, and are omitted in the map. 
A comparison was made on four occasions of the dip observed on board ship when 
in harbour, and with the same instrument taken on shore. These were as follows : 
Falmouth, July 6th, 1838. 
On shore . Dip 69 12*5 
In the Arrow, ship’s head W.N.W 69 27 
Rio de Janeiro, September 4th, 1838. 
On shore - l 3 00-5 
In the Arrow, ship’s head S. by E — 13 56 
In the Arrow, ship’s head W.S.W _ 13 37 
Rio de Janeiro, April 4th, 1839. 
0n shore - 13 00*5 
In the Stag, ship’s head N. by W — 1310 
Pernambuco, May 7th, 1839. 
Onshore 13 08*5 
In the packet Opossum, head N.N.E 13 10 
s 2 
