ATMOSPHERIC PRESSURE. 277 
The daily means in this Table have been obtained from the nine daily observations in the following man- 
ner :—If § be the sum of the nine observations from 18» till 10", 18 be the height at 18", 10, the height at 
105 preceding the 18", and 10, the height at 10 succeeding the 18%, then the daily means for the Mondays 
were obtained from the formula, 
2x 18+8 +10, 
12 
and for the other days of the week from the formula, 
10,4 181+ 8 4-410) 
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 0605 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. 
in. in. in. 
Spring, . .  29°590 29-577 29549 
Summer, . 4 638 “743 *626 
Autumn, . . -605 614 *665 
Winter, : 2 606 -606 699 
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. 
5 . After a After 
Number | Height | yyoon7, | Number} Height || yyoon Height iaan 
of of of ] of 
Age. } farth 
Barometer.) ~“5° Barometer. aes | . |Barometer.| — ae 
in. 5 in. 
29-732 0 29-611 
+593 485 
-653 +559 
-702 572 
‘751 -480 
723 +493 
674 -580 
-698 -640 
+582 -688 
-622 -606 
-685 713 
-560 671 
-628 672 
+553 -664 
-623 +658 
1] 
WCHONIAMNHRwWWR OF 
This Table has been formed from Table XV. in the manner already referred to, Table X. 
MAG. AND MET. oBs. 1843. 4a 
