282 ABSTRACTS OF THE MAKERSTOUN OBSERVATIONS, 1843. 
The monthly means exceed the means of the highest and lowest readings in each month excepting May, 
the mean of the twelve monthly maxima and minima being 0-118 in, less than the mean for the year. 
The monthly means exceed the means of the highest and lowest daily means in each month with the ex- 
ceptions of May and November; the mean of the twelve monthly maxima and minima of daily means being 
0-069 in. less than the mean for the year.* 
TABLE XX.—Daily, Weekly, and Monthly Means of the Pressure of the Dry Air in 1843. 
Civil | Jan. Feb. March. | April. May. June. July. Aug. Sept. Oct. Nov. Dec. 
] in. in. in. in. in. in. in. in. in. in. in. in. 
1 |Leereeee J) 29-035 | 29-468 | 28-704 | 29-920 | 29-009 | 29-184 | 29.102 | 29-576 |[29-353]} 29.322 | 29-712 
2 29-747 | 28-910 | 29-714 |[25-968]| 29-814 | 28-700 [29-159]) 28-854 | 29-549 | 29-400 | 29-409 | 29-640 
3 29-710 | 28-748 | 29-849 | 29-097 | 29.436 | 28-911 | 29-067 | 28-716 |[29-637]| 29-443 | 29-126 |[29-577] 
4 29-263 | 29-296 | 29-951 | 28-906 | 29-113 |[29-094]) 29-315 | 28-773 | 29-756 | 29-371 | 29-032 | 29-624 
5 || 29-440 |[29-359]|[29-824]] 29-129 | 29-045 | 29-429 | 28-987 | 29-080 | 29-808 | 29-298 |[ 29-140) 29-277 
6 29.502 | 29-678 | 29-685 | 29-049 | 29-025 | 29-392 | 28-983 |[29-132]| 29-565 | 28-787 | 29-144 | 29-583 
7 | 29.072 | 29-785 | 29-781 | 28-783 |[29-286]| 29-127 | 29-195 | 29-403 | 29-676 | 28-697 | 28-982 | 29-368 
8 ||[28-917]| 29-738 | 29-962 | 28-904 | 29-328 | 28-515 | 29-300 | 29-340 | 29-638 |[28-964]| 29-148 | 29-607 
9 28-763 | 29-792 | 29.914 |[29.224]| 29-478 | 28-504 |[29-347]| 29-482 | 29-543 | 29.062 | 29.411 | 29-689 
10 28-266 | 29-800 | 29-596 | 29-528 | 29-727 | 29-107 | 29-480 | 29-565 \[29-574]) 29-262 | 29-078 |[29-650] 
11 28-458 | 29-830 | 29-589 | 29-612 | 29-711 |[29-175]] 29-648 | 29-567 | 29-319 | 28-680 | 29-557 | 29-656 
12 28-528 |[29-593]|[29-413]| 29-465 | 29.495 | 29-687 | 29-477 | 29-569 | 29-618 | 28-858 |[29-543]| 29-820 
13 27-820 | 29-605 | 29-012 | 29-528 | 29-141 | 29-644 | 29-410 |[29-488]| 29-646 | 29-112 | 29-716 | 29-757 
14 28-233 | 29-416 | 28-995 | 29-185 |[29-320]| 29-596 | 29-412 | 29-492 | 29-403 | 29-360 | 29-883 | 29-657 
15 ||[28-847]| 29-117 | 29-373 | 29-463 | 29-101 | 29-621 | 29-341 | 29-372 | 29-309 |[29.223]) 29-612 | 29.562 
16 29-261 | 28-972 | 29-497 |[29-423]| 29-103 | 29-583 |[29-303]| 29-357 | 29-363 | 29-201 | 29-588 | 29-837 
17 29-548 | 29-277 | 29-236 | 29-487 | 29-369 | 29-557 | 29-440 | 29.349 |[29-429]| 29-164 | 29-111 |[29-754] 
18 29-692 | 29.443 | 29-368 | 29-511 | 29-602 |[29-544]| 29-105 | 29.374 | 29-390 | 29-644 | 28-858 | 29-902 
19 29-875 |[29-174]|[29-198]| 29-362 | 29-639 | 29-536 | 29-109 | 29-150 29-702 | 29-928 |[28-983]| 29-874 
20 29-776 | 29-160 | 29-301 | 29-248 | 29-489 | 29-588 | 28-975 |[29-136]| 29-406 | 29-518 | 28-848 | 29.694 
21 29-556 | 29-107 | 28-925 | 29-241 |[29-417]) 29-377 | 29-023 | 29.268 | 29-532 | 29-331 | 28-771 | 29-776 
22 [29-475] 29-082 | 28-859 | 29-233 | 29-251 | 29-490 | 28-965 | 28-747 | 29-882 |[29-319]| 28-724 | 29-476 
23 || 29-292 | 29-167 | 28-947 |[29-230]| 29-277 | 29.492 |[29-226]| 28-931 | 29-943 | 29-214 | 28-970 | 29-611 
24 || 29.084 | 29-328 | 29.333 29.537 | 29-243 | 29-514 | 29-485 | 29-167 |[29-703], 29-002 | 29-157 |[29-720] 
25 || 29.265 | 29-374 | 29-637 | 29-031 | 28-989 |[29-419]) 29-559 | 29-137 | 29-818 | 28-921 | 29-209 | 29-805 
26 29-353 |[29-2031/[29-463]| 29-091 | 28-884 | 29-420 | 29.350 | 29-236 | 29-671 | 29-078 |[29-201]| 29-808 
27 || 29-030 | 28-846 | 29-618 | 29-345 | 28-813 | 29-331 | 29-368 |[29-270]| 29-372 | 29-095 | 28-776 | 29-842 
28 || 29.036 | 29-034 | 29-600 | 29-126 |[29-149]| 24-269 | 29-293 | 29-107 | 29-405 | 28-322 | 29-348 | 29-899 
29 [29-081] 29-646 | 29-304 | 29-469 | 29-227 | 28-838 | 29-357 | 29.417 |[28-990]| 29-747 | 29-787 
30 | 29-001 29-212 |[29-491]| 29-499 | 29-172 |[29-109]) 29-611 | 29-082 | 29-058 | 29-626 | 29-511 
31 | 29-030 28-764 29-238 29-199 29-566 29-063 [29-463] 
| 
=) 
Mean || 29-138 | 29-314 | 29-438 | 29-235 | 29-341 | 29-300 | 29.250 | 29-247 | 29.553 | 29-149 
29-237 | 29-683 
This Table has been formed by subtracting Table IX. from Table XV. 
Annual Variation of the Pressure of Dry Air—The pressure of the dry air is least in January, being 
29-138 in.; it increases from thence till March, then diminishes in April; after a slight increase in May it 
diminishes till August, the pressure being nearly the same in that month as in April ; it then increases con- 
siderably in September, and diminishes to a greater extent in October and November; the greatest pressure 
oceurs in December, being 29-683 in, The range of the monthly means is therefore 0-545 in. If the pressure 
in December be kept out of view, the annual variation for 1848 indicates maxima in the equinoctial months, 
and minima near the solstices. The following are the means for the three different groups, namely, 
* L have pointed out elsewhere (Transactions of Sections, Report of Brit. Assoc. 1845, p. 15), that the means of the monthly 
maxima and minima are probably always less than the mean pressure in certain latitudes (including 50° and 60° north), but that in 
other latitudes the reverse is the case. The explanation of this fact will probably be found in the prevalence and excessive pressures 
of particular winds. 
