MIto i
TABLE IV.
I n th e construction o f this table my object was to ascertain the periodical oscillation and mean
pre ssure o f the atmospliere in th e open sea, in different p arts of the globe, where th e observations
are uninfluenced by local disturbances inseparable from those made ou shore. T h e observations
besides possess the advantage o f b ein g made with th e same instrument, and u n d e r similar circumstances,
in places widely situa ted from each other, and consequently o f exhibiting a relative
measure free from th e inaccuracies which are liable to arise from comparisons of re sults by
different barometers. I tru s t th a t th e len g th o f th e series has in a g re a t measure overcome the
irreg u larities to which such delicate observations are liable on board a ship constantly in motion.
T h e in strum en t used was an iron cistern marine barometer of Jo n es’s make ; neutra l point
3 0 .1 0 2 ; capacity temperature 52°. I t was suspended in my fore cabin, and, with th e e x c e p -,
tio n o f th e first five months, reg iste red eve ry th ree hours, b eginning a t noon.
Between th e tropics, where th e variation o f the tem p eratu re is trifling, and where the hora ry
oscillations are increased, and suffer fewer interru p tio n s from changes in the atmospherical tides,
I have given th e mean altitude for ev e ry five degrees o f latitude on each side of th e equator, and
in the extra -tropica l latitudes to eve ry five or six days. I t would have b een belter, no doubt,
to have given th e re sults of different parallels th ro u g h o u t; b u t th e table being differently cons
tru cted a t first, I did n o t th in k it necessary to make the alteration, particularly as the observations
re q u ire to be corrected for tem p e ra tu re ; and in such a series o f observations th e time th a t would
hav e been necessary for this purpose was more th an I could spare to have had the tables ready
in an y re asonable time. Such persons, however, as are curious in this m atter can make th e corrections
for themselves on re fe rrin g to th e data contained in this and th e following table, or to
m y m eteorological jo u rn a l, which will be deposited in th e Hydrographical Office for this purpose.
N O R T H A T L A N T IC O C E A N .
Latitude.
BAROMETER. Mean
Date. A.M. P.M.
tcmpera-
North. West. 3 a Nood. 3 9 Midnight. Mercury.
1825.
June 7-
— 8.
— 9.
24 8
21 57
20 1
0
19 21
21 17
23 24
30.140
.139
.025
30.140
.160
.093
30.150
.160
.023
30.180
.160
.080
30.160
.082
.127
30.170
.136
.158
30.156
.139
.121
70.87
72.40
73 60
25« to 20« 19«to 25« 30.101 30,131 30.111 30.140 30.123 30.155 30.139 72,29
— 10.
— 11.
18 .37
17 29
25 28
26 59
.100
30.250 30.150 30.ÌOO
30.080
.048
30.140
.140
30.130
.197
30.112
.130
74.31
74.54
20« to 15« 25« to 27« 30.125 30.150 30.100 30.064 30.140 30.113 30.121 72.42
— 12.
~ 13.
— 14.
15 36
13 24
11 8
27 39
47
18
30.105
.020
.040
30.070
.100
.080
30.079
.155
.130
30.105
.080
.028
30.135
.120
.047
30.072
.080
.080
30.094
,092
.067
76.40
76.77
77-70
15«to 10« 27°toO 30.055 30.083 30.121 30.071 30.101 30.077 30.084 76.95
— 15.
— 16.
- 17.
— 18.
8 9
7 21
7 2
6 25
27 17
26 39
25 48
26 15
30.100
.020
.090
.021
30.079
.068
.050
.070
30.030
.184
.T37
30.100
29.920
.994
30.090
30.177
.090
.036
.100
30.100
.040
.020
.057
30,083
.053
.038
.079
78.62
78.63
78.29
79.75
10« to 5° 27« to 26« 30.058 30.067 30.117 30.026 30.101 30.054 30.063 78.82
Longitude.
BAROMETER. Mean
tempera-
Date. A.M. P.M. Mean
North. West. 3 9 Noon. 3 9 Midnight. Mcrcury.
1825.
J u n e 19.
— 20.
^ 21.
- 22.
- - 23.
5 33
4 6
3 2
2 42
1 30
25 50
26 41
26 4
27 41
28 23
30.000
29.970
30.042
.000
29.980
30.082
.010
.020
.075
.050
30.084
.100
29.990
30.100
.050
30.020
29.980
30.130
.040
29.960
30.020
.010
.092
.000
.020
30.030
.020
.055
.050
.030
30.039
.015
.054
.044
.010
79,41
81.04
79.83
80,20
80.00
5» to 0« 26« to 28« 29.998 30.047 30.065 30 026 30.028 30.037 30 033 80.09
S O U T H A T L A N T IC O C E A N .
J u n e 24.
— 25.
— 26.
- 27.
South.
8
1 5
3 5
5 7
West.
30 8
46
31 24
32 26
30,082
.060
.000
29,960
30.020
.045
.100
.060
30.020
.130
.080
29.960
30.020
.040
29.900
30.030
30.083
.070
.020
.160
30.110
.070
.080
.130
30.055
.069
.030
.050
77.00
79.06
77-87
79.08 •
0« to 5« 30« to 330 30.025 30.056 30.047 29.997 30.083 30.097 30.051 78-25
— 28.
— 29.
— 30.
6 48
8 27
10 4
33 13
34 10
0 33
30.060
.170
.100
30.160
.150
.170
30.160
.120
.050
30,050
29.940
30.080
.090
.175
30.130
.100
.175
30.106
.061
.134
78.92
78.08
77.75
5« to 10« 33«to 34« 30.110 30.160 30.110 29.995 30.115 30.135 30.104 78.25
J u ly 1.
- 2.
12 25
15 19
34 31
35
30.020
.120
30.175
.180
30.169
.150
30.160
.180
30 130
.160
30.180
.100
30.139
.148
78.50
77.43
10«to 15« 34« to 35« 30.070 30.177 30.159 30.170 30.145 30.140 30.143 77-96
— 3.
— 4.
17 31
19 14
35 46
36 36
.160
.090
.220
.165
.160
.170
.140
.160
.160
.220
.170
.160
.166
.160
75.27
76,00
15« to 20« 35« to 37« 30.125 30.192 30,165 30.150 30.195 30 165 30,163 75.63
— 6.
— 7.
— 8.
— 9.
— 10.
— 11.
20 35
20 42
20 54
21 33
23 16
23 14
37 17
38 34
38 46
39 32
40 35
Off Rio-
J anciro.
30.120
.120
.180
.100
.100
.100
.180
30.200
.140
.247
.150
,070
.234
30,140
.140
.245
.180
.160
.228
.200
30.150
.220
.040
.080
.100
.180
.106
30.120
.220
.180
.093
.160
.170
.140
30.120
226
.180
.100
.140
.150
.120
30.141
.194
.178
.117
.120
.177
.149
71.32
70.41
69.97
71.14
69 50
68.95
20« to 23' 37° to 43« 30.128 30.173 30.184 30.125 .30.151 30.148 30.152 70.22
A u g u s t 16.
- 17-
— 18.
— 19.
— 20.
— 21.
23 8
26 29
27 49
28 52
30 1
31 15
44 29
44 37
45 6
46 19
18
30.140
30 000
29.960
,960
30.000
30.120
29.940
.880
.980
.940
30.040
30120
29.810
.950
30.020
29.940
30.080
30 087
29.840
.990
30.020
29.930
30.050
30.080
29 970
30.020
29.948
.990
30.140
29.970
30.040
.020
.000
.100
30.108
29.906
.980
.991
.960
.068
68.00
6 700
66 00
66.62
68.25
66.91
23« to 31' 43« to 45' 30.012 29 983 29.986 29.986 30.024 30.026 30 002 67.13