ATMOSPHERIC PRESSURE. 279 
The diurnal ranges have been obtained, in the first week in January, by taking the differences of the highest 
and lowest readings included between the first observation on the civil day and the first observation of the next 
civil day ; the range for the 7th (Saturday) was obtained by including the last observation on the 6th. For 
the remainder of the year, the range for Mondays was obtained by including the first observations of Tuesday, 
and the range for the other days of the week by including the last observations of the previous days. 
Mean of the Diurnal Ranges of the Atmospheric Pressure.—The diurnal ranges are least in May, the mean 
for that month being 0-151 in., and greatest in November, the mean being 0°355 in. The following are means 
for the three classes of groups, namely, 
The mean meteorological seasons, for which June, July, and August constitute summer. 
The meteorological seasons for the year 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,  . . 0-197 0:185 0:207 
Summer, s x 176 175 “177 
Autumn, : : 268 282 205 
Winter, c ; 248 "243 301 
Range of Means, . 0-092 0-107 0-130 
The diurnal ranges are least for Summer of all the groups, and greatest for Autumn in the two meteoro- 
logical groups, but greatest for Winter of the astronomical group. ‘The latter group seems the most distinct, 
the difference of the means is also greatest for it. 
The mean of all the diurnal ranges for the year 1843 = 0-221 inch. 
TABLE XVIII.—Hourly Means of the Height of the Barometer for each Month and Quarter 
of 1843. 
Period. 18%, 6, 8h, 10», || Mean |! Range. 
Pressure. | ‘2 
in. in. in. in. in. in. in. in. in. in. | in. 
January 29-333 | 29-353 | 29-363 | 29-365 | 29-353 | 29-357 | 29-358 | 29-367 | 29-374 | 29-357 | 0-041 
February 474 -482 “501 “511 498 493 501 “O15 -520 -499 || -046 
March 647 -662 -669 -670 -662 -656 -658 -670 -672 || -662 | -025 
April -480 484 -486 -484 477 -472 477 494 -507 487 || -035 
May -633 -636 “634 -628 ‘619 -606 -098 -607 -610 -620 || -038 
June -614 621 -624 -627 -624 -616 -608 -613 +622 “619 || -019 
July -64] ‘641 -641 642 +633 -629 +622 +627 -632 -635 -020 
August +662 669 -668 -660 +652 -641 635 “645 -657 | -656 -034 
September -926 -941 949 -944 933 -926 -926 +935 -941 -935 | -023 
October -402 414 419 -415 407 +394 -389 391 -391 -401 -030 
November -431 -441 -460 -470 476 -481 -493 -499 -503 471 || .072 
December -962 -962 -975 ‘977 +959 +953 ‘956 +957 ‘961 -962 -024 
| 
Spring -587 +594 596 “594 -586 | ‘578 -578 590 -596 -590 -018 
Summer +639 -644 -644 -643 ‘636 -629 +622 -628 ‘637 -637 || -022 
Autumn 586 -599 -609 610 ‘605 | -600 -603 -608 -612 -602 -026 
Winter -590 -599 -613 -618 -603 -601 -605 613 -618 -606 || -028 
| | 
The Year -600 -609 -616 ‘616 -608 -602 -602 -610 -616 -609 -016 
t 
