Atmospheeic Pressure. 
277 
The daily means in this Table have been obtained from the nine daily observations in the following man- 
ner : — If S be the sum of the nine observations from 18 h till 10 h , 18 be the height at 18 h , 10^ the height at 
10 h preceding the 18 h , and 10 s the height at 10 h succeeding the 18 h , then the daily means for the Mondays 
were obtained from the formida, 
2 x 18 + S + 10, 
12 
and for the other days of the week from the formula, 
10 p + 18 + S + 10, 
12 
It was found, from other observations, that means thus obtained differed very little from the truth. 
Annual Variation of Atmospheric Pressure. — The lowest monthly mean pressure is that for January, 
being 29 - 358 in. ; the highest monthly mean pressure is that for December, being 29-963 in. ; the range of 
the monthly means is therefore 0-605 in. The following are the mean pressures for three different classes of 
seasons, viz. : — 
The mean meteorological seasons, for which June, July, and August constitute summer. 
The meteorological seasons of 1843, for which July, August, and September constitute summer. 
The astronomical seasons, for which May, June, and July constitute summer. 
Seasons. 
Mean Meteorological. 
Meteorological for 1843. 
Astronomical. 
Spring, 
in. 
29-590 
in. 
29-577 
in. 
29-549 
Summer, 
•638 
•743 
•626 
Autumn, 
•605 
•614 
•665 
Winter, 
•606 
•506 
•599 
Range of Means, 
0-048 
0'237 
0-116 
The second group is the most marked ; it indicates the maximum pressure in the warmest quarter of 1843, 
and the minimum in the coldest quarter. 
in. 
The mean pressure for the year = 29-610. 
TABLE XVI. — Height of the Barometer, with reference to the Moon's Age and Declination 
for 1843. 
Moon's 
Age. 
Number 
of 
Days. 
Height 
of 
Barometer. 
Moon's 
Age. 
Number 
of 
Days. 
Height 
of 
Barometer. 
After 
Moon 
farthest 
North. 
Number 
of 
"Days. 
Height 
of 
Barometer. 
After 
Moon 
farthest 
North. 
Number 
of 
Days. 
Height 
of 
Barometer. 
Days. 
in. 
Days. 
in. 
Days. 
in. 
Days. 
in. 
15 
9 
29-732 
6 
12 
29-611 
0 
11 
29-558 
14 
11 
29-566 
16 
11 
•593 
l 
10 
•485 
1 
12 
•587 
15 
12 
•599 
17 
10 
•653 
2 
11 
•559 
2 
9 
•561 
16 
9 
•859 
18 
11 
•702 
3 
9 
•572 
3 
11 
•516 
17 
11 
•585 
19 
10 
•751 
4 
11 
•480 
4 
12 
•582 
18 
12 
•712 
20 
9 
•723 
5 
10 
•493 
5 
11 
•687 
19 
11 
•770 
21 
12 
•674 
6 
9 
•580 
6 
12 
•744 
20 
12 
•694 
22 
9 
•698 
7 
12 
•640 
7 
11 
•743 
21 
11 
•593 
23 
11 
•582 
8 
10 
•688 
8 
12 
•600 
22 
12 
•667 
24 
10 
•622 
9 
11 
•606 
9 
9 
•641 
23 
9 
• 561 
25 
11 
•685 
10 
9 
•713 
10 
11 
■483 
24 
11 
•685 
26 
10 
•560 
11 
11 
•671 
11 
12 
•492 
25 
12 
•532 
27 
9 
•628 
12 
10 
•672 
12 
11 
•514 
26 
11 
•646 
28 
11 
•553 
13 
9 
•664 
13 
12 
•580 
27 
11 
•688 
29 
9 
•623 
14 
12 
•658 
This Table has been formed from Table XV. in the manner already referred to, Table X. 
MAG. AND MET. OBS. 1843. 4 A 
