Atmospheric 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 IS'^ till lO'^, 18 be the height at 18^, 10^, the height at 

 lO** preceding the 18*^, and 10^ the height at 10'' succeeding the IS'', then the daily means for the Mondays 

 were obtained from the formula, 



2 X 18 + S + 10, 



12 



and for the other days of the week from the formula, 



lOp + 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. 



Spring, 



29-590 



Summer, 



-638 



Autumn, 



-605 



Winter, 



-606 



Meteorological for 1843, 



in. 



29-577 

 -743 

 •614 

 -506 



Astronomical, 

 in. 



29-649 

 •626 

 •665 

 •599 



Range of Means, 



0048 



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 raean 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. 



15 



9 



in. 



29-732 



Days. 







12 



in. 



29-611 



Days. 







11 



in. 



29-558 



Days. 



14 



11 



in. 



29-566 



16 



11 



•593 



1 



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 



2.3 



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 



