422 



Results of Makerstoun Observations, 1844. 



These means vary with great regularity. The diurnal range of atmospheric pressure was greatest when 

 the moon was farthest north, and it was least when the moon was farthest south. The mean of 84 diurnal 

 ranges about the time of the moon's greatest northerly position was 0-052 in. greater than the mean of the 

 same number of ranges about the time of the moon's greatest southerly position. 



TABLE XXI. — Hourly Means of the Height of the Barometer for each Month, and the Year 1844. 



Mak. t 

 M. T. 



an. 



Feb. Ms 



urch. A 



jril, IV 



[ay. J 



me. 



July. 



Aug. 



Sept. 



Oct. 



Nov. Dec. "5 



['ear. 



h. 



m. 



in. 



n. 



in. 



m. 



m. 



in. 



in. 



in. 



in. 



in. 



in. 



in. 



12 29 



695 



29-307 29 



511 29 



811 29 



988 29 



631 



29-641 



29-493 



29-828 



29-397 



29-553 29 



892 29 



6456 



13 



691 



•300 



511 



805 



982 



629 



•638 



•489 



•825 



•392 



•549 



887 



6415 



14 



690 



•295 



506 



802 



981 



623 



•633 



•483 



•819 



•385 



•548 



888 



6377 



15 



690 



•290 



504 



800 



978 



621 



•629 



•478 



•814 



•378 



•544 



885 



6342 



16 



686 



•287 



506 



796 



981 



624 



•632 



•475 



•811 



•375 



•545 



879 



6331 



17 



684 



•289 



507 



802 



987 



628 



•635 



•479 



•812 



•374 



•544 



876 



6347 



18 



684 



•290 



511 



807 



991 



631 



•638 



•485 



•820 



•376 



•544 



878 



6379 



19 



687 



•299 



513 



811 



995 



632 



•638 



•488 



•825 



•387 



•550 



883 



6423 



20 



695 



•312 



517 



812 



997 



635 



•637 



•489 



•827 



•395 



•559 



891 



6472 



21 



701 



•318 



523 



811 



996 



635 



•635 



490 



•830 



•400 



•565 



899 



6502 



22 



706 



•325 



526 



809 



993 



634 



•629 



•489 



•826 



•401 



•572 



904 



6512 



23 



698 



•334 



529 



805 



988 



629 



•630 



•490 



•821 



•401 



•572 



899 



6497 







692 



•336 



528 



802 



982 



630 



•629 



•487 



•817 



•397 



•567 



889 



6463 



1 



686 



• 336 



526 



801 



977 



627 



•629 



•486 



•813 



•396 



•564 



884 



6437 



2 



685 



•333 



527 



795 



970 



625 



•621 



•486 



•806 



•397 



•562 



884 



6409 



3 



689 



•333 



528 



793 



962 



624 



•616 



•485 



•803 



•394 



•564 



887 



6398 



4 



692 



• 334 



533 



794 



959 



621 



•609 



•485 



•801 



•399 



•565 



888 ! 



6400 



5 



694 



•337 



542 



794 



959 



617 



•603 



•484 



•803 



•404 



•569 



890 j 



6413 



6 



697 



•340 



549 



799 



962 



620 



•603 



•489 



•808 



•412 



•573 



893 



6454 



7 



700 



•344 



557 



806 



970 



622 



•607 



•494 



•815 



•414 



•575 



899 



6502 



8 



698 



• 343 



556 



812 



978 



625 



•611 



•500 



•819 



•418 



•577 



903 



6533 



9 



700 



•340 



558 



814 



983 



627 



•616 



•504 



•818 



•416 



•579 



905 



6550 



10 



700 



•337 



559 



814 



983 



625 



•621 



•507 



•821 



•412 



•580 



907 



6555 



11 



694 



•336 



561 



814 



983 



626 



•622 



•507 



•819 



•406 



•582 



907 



6547 



Diurnal Variation of Atmospheric Pressure. — The means for each month indicate two maxima and two 

 minima ; the epochs, however, vary considerably ; this is chiefly due to rapid variations of mean pressure, and 

 especially to those which occur between Saturday night and Monday morning; these render the mean at ll h 

 (the hour of the last observation on Saturday) considerably different from that at 12 h (the hour of the first 

 observation on Monday morning). Assuming that the change in the means from ll h to 12 h is the same as 

 from 10 h to ll h , the differences between the means for 12 h so obtained, and the means for 12 h at the com- 

 mencement of each series, will be due to the causes noticed above, and they may be considered as differences 

 which have gradually increased from the first to the following 12 h . By correcting the observations for such 

 gradual changes, the epochs of maxima and minima will be determined with more accuracy. Table XXII. 

 has been formed in this way. The hourly means of the astronomical quarters having been obtained, the change 

 from the preceding to the following 12 h was found — 



For Winter, =+0-0131. 

 For Spring, = +0-0270. 



Correction, 



:-0-00055 an hour. 

 :-000112 



For Summer, = -0-0090. Correction, = + 0-00037 an hour. 

 For Autumn, = 0-0000. 



For the means for the year, = + 0-0083. Correction, = —0*00035 an hour. 



The number of the hour after 12 h being n. the hourly means for the quarters were corrected by the quan- 

 tities nx c, where c is the correction given above for the respective quarters ; the numbers for each quarter 

 and the year, in excess of the lowest mean thus corrected, are given in Table XXII. 



