l i t r i
■'i'ri
I¡ i'i.all i i.
over th e margin of th e ice. As the heavy clouds reached this spot th ey we re gradually con*
deiised, the effect of which was precisely similar to tliat which sometimes occurs about the
summits o f high mountains, ag a in st which th e clouds are successively driven, without any
b e in g seen to depa rt, and without any ap p a ren t increase.
T h is remarkable disturbance of the equilibrium of th e atmosphere being admitted,
I would here mere ly suggest wliether, u nder ce rtain dispositions of th e atmosphere, electricity
mig h t n o t be induced and communicated to th e surrounding region, so as to occasion
the Aurora BoreaUs, and to account for its appearance in tlie before-mentioned directions in
preference to others.
I am n o t aware what would be the effect o f the mee ting o f two atmospheres, one influenced
b y a large body o f ice, th e other by an e.xtensive continent, such as th a t o f America,
and particula rly when th e circumstances mig h t be modified by large frozen lakes. B u t it
appears from Captain F ran k lin ’s observations a t G re a t B ear Lake , th a t th e Aurora arose in
almost all quarte rs of th e horizon, and more freq u en tly illuminated his zenith than the Auroras
appe ar to have done eith e r of those a t the before-mentioned places.
O u r observations we re too limited to ju stify any remark on the observation o f Captain
Franklin, th a t th e appearance o f th e Aurora occurs more frequently in th e last quarters
of th e moon than in others.
TABLE IX.
SPECIFIC GRAVITY OF SEA WATER.
I n the first p a rt of this Table th e specific g rav ity o f th e surface o f the sea, reduced to the
temperature of 60", and corrected for th e error o f the hydrometer, is given for ev e ry second deg
re e of latitude. In th e la s t it is arranged according to th e passages, and the observations are
uncorrccted. In re ducing them it will be necessary to apply + .0375 for th e erro r of th e in-
strument, a t the temperature of 60«.
NORT'H ATLANTIC. SOUTH ATLA NTIC. SOUTH ATLA NTIC.
Lati.
ludo.
Long.
West
Date.
Specific
Gravity,
temp. 60«.
Long.
YY'est.
Date.
specific
Gravity,
temp. 60®.
Long.
West.
Date.
Specific
Gravity,
temp. 60«.
1825. grains. 1825. grains. 1828. grains.
24
28
28
June 22
21
1028.18
7.68
31
32
Jime 25
26
1028.18
8.51
24 Aug. 20 1028.22
6
8
26
27 ,
18
15
7.00
7-48
33 27 8.51 24 ' 19 8.17
10
12
14
16
27
28
27
27
14
13
12
11
7-89
7.80
8.08
7.91
' 3 5 '
35
' 3 5 ’
' 3Ò
July 1
2
8.74
8.88
8.71
25
to
26
' 18
17
16
8.70
8.70
8.70
18
20
25
23
10
9
8.13
8.09
35
to
36
8.76
8.40
27
28
15 , 8,90
22
24
21
20
87
1828.
8.32
8.36
41 9 8,19 ’ 13
12
8.78
8.88
2 6 ’ ’ 3 4 ' Sept. 3 1030.06
to
10 0 00
28
30
32
34
36
’ 1 5 '
17
Sept. 10
1825.
May 31
30
1029.38
8.26
8.22
45 Aug. 22 8.00 44
IU9
July 12
11
0.00
9,08
8.34
8.34
36 16 29 8.20 48 ‘ 26 7-72 36 ’ 1Ó 8.08
40
42 ’ 1 5 ’ ■ 27 ¿ 7 7
46
45
47
27
28
Sept. 2
7.50
7.44
6.76
38 7 8.24
44 14 26 7.64 48 3 6.84 46 13 25 7.50 51 5 7.86 48 10 23 7.36 47 7 7.15
RNs t /■
ir ym