xc GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS 
The mean pressure for the six months October to March is 0:100 inch less than that for the six months 
i 
April to September, while the range of the quarterly groups for the meteorological seasons is only 0-057 in. . 
> 
rf 
Neglecting therefore the minor variations, the law of atmospheric pressure is distinguished by a maximum for 
the six months during which the sun is north of the equator, and a minimum for the six months during which 
it-is south of the equator. ‘The means for the separate quarters show no direct connection with temperature, 
since April to June, and July to September have nearly the same mean pressure, 
TABLE 84.—Mean Differences of the Daily Mean Atmospheric Pressure from the Monthly 
Mean, for each Month in the Years 1843-6. 
Feb. | March. 
in. ha 
0-261 | 
-310 | 
-208 
+325 
276 
192. Annual Variation of the Differences of the Daily Mean from the Monthly Mean Pressure —From 
the means for four years in Table 84, the daily mean pressure of the atmosphere varied most in the months of 
November and January, and it varied least in July. The following groups give the greatest and least quarterly 
means,— ; 
Nov. Dec. Jan. Feb. Mar. April, May, June, July, Aug. Sept. Oct. 
in. in. in. in. 
0:300 0:258 0°203 0:246 
The daily mean height of the barometer differs on the average three tenths of an inch from the monthly 
mean in the winter quarter, Nov.—Jan., and only ¢wo tenths of an inch in the summer quarter. 
‘TABLE 85.—Monthly Means of the Diurnal Ranges of the Atmospheric Pressure for the 
Years 1843-6. 
a 
Year, Jan. | Feb. | March.| April. | May. | June. | July. | Aug. | Sept. Oct. Nov. Dec. | Mean. 
| | 
| in. | in. in. in. in. in. in. in. in. in. in. in. | in, 
1843 | 0-342 | 0-180 | 0-206 | 0-235 | 0-151 | 0-169 | 0-194 | 0-166 | 0-165 | 0-285 | 0-355 | 0-207 | 0.221 
1844 224 | .282| .298 | -185 | -124] -148 | -156 | -181 | -134 | -234 | -196 | -145 | -192 
1845 320 | -243 | .236 | -222 | -131 | -184| -181 | -164 | -223 | -208 | -269 | -452 | +236 
1846 || -283 | -202 | -269 | -160 | -183 | -142 +172 | -149 | -165 | -294 | -223 | -217 | +205 
Mean | .292 | -227 | .252 | .200| -147 | -161 | -176 | -165 | -172 |] -255 | -261 | -255 || -214 
193. Annual Variation of the Diurnal Range of the Atmospheric Presswre,—From the means of the diurnal 
ranges for each month in the four years 1848-6, the diurnal range is least in May, and it is greatest in 
January ; the following groups give the greatest and least quarterly means,—— 
Nov. Dec. Jan. Feb. Mar. April, May, June, July, Aug. Sept. Oct. 
= = in. i 
in, in. in. 
0-269 0226 0-161 0197 4 
