300 ABSTRACTS OF THE MAKERSTOUN OBSERVATIONS, 1843. 
Diurnal Variation of the Resolved and Resultant Pressures of the Wind.—The sums resolved in the E. 
attain their maximum latest in the day, about 2" p.w; the sums resolved in the W. attain their maximum 
earliest, about Noon; while the sums resolved in N, and in 8S. attain their maximum about 12 p.m. The re- 
sultant sums of pressures attain their maximum about 0? 30™ p.m., minima occur about 7" a.m. and 8» p.m. 
The mean resultant attains a maximum about Noon, the minimum occurs about 3" 40™ p.m.; the maximum 
probably occurs near midnight, a secondary minimum occurs about 7" a.m. 
The Direction of the Resultant seems to have a diurnal variation, being more towards the south of west in 
the morning and evening than about mid-day. 
TABLE XXXIII.—Differences of the Directions of Motions of the Lower and Upper Currents of Air, 
as deduced from the Comparisons of the Direction of the Wind and Motions of the Clouds. 
Quadrant N. to B. Quadrant E. to 8. Quadrant S. to W. Quadrant W. to N. 
Currents. 
No. of |Diffs.of| Mean || No. of | Diffst of | Mean || No. of |Diffs.of| Mean || No. of |Diffs.of| Mean 
Obs. | Motion.) Diff. Obs. | Motion. | Diff. Obs. | Motion.) Diff. Obs. |Motion.| Diff. 
° ° ° ° ° 
Scud minus 
75 : 177 |+23-7 +18-5 
Wind 
30 : 20 |—22-6 — 32-3 
Cir.-str. minus 
Wind 
15 : 87 |4+47-6 + 26:8 
14 : 12 |-23-7 — 46-6 
Cir.-str. minus 
‘| 57 |+34-5 + 20-3 
Scud 
14 |—19-7 — 50-7 
Cirri minus 
Wind 
| : 42 |+46-7 +23-9 
7 |-38-6 — 50:6 
Scud 
Cirri minus | +32-7 +19-8 
— 35-6 | — 87-2 
This Table has been formed by taking the differences of the motions of the surface wind as observed on 
the anemoscope and the motions of the clouds. In order to arrive at any definite result, it was necessary to 
group the comparisons into quadrants of the compass. In several quadrants there are still too few comparisons 
to give satisfactory results. 
The first column under each quadrant contains the number of times which an upper current was observed 
to proceed from a point plus, and the number of times which it was observed to proceed from a point minus, 
the direction of a lower current, from N. to E., 8. and W. being the direction of reckoning. The second column 
under each quadrant contains the mean of the positive differences, and also the mean of the negative differences ; 
the third column contains the mean difference of the motions from all the observations. Taking the first case for 
an example—the wind blowing from a point between N. and E, the scud was observed on 75 occasions to be 
moving from a point on an average of 27°-9 south of the point from which the wind was blowing ; and on 30 
occasions from a point on an average 44°2 north of the point from which the wind was blowing. From ail the 
105 observations, the scud was found to move from a point 7°-4 south of that from which the wind blew. 
In every quadrant, the upper currents were observed more frequently to be moving from points plus than 
from points minus those of the lower currents. In every quadrant, however, excepting S. to W., the average 
difference (with two exceptions) is greater for the minus than for the positive observations. In the quadrant 8. 
to W. this is not the case; not only are the number of observations greatest for the upper current positive of 
the lower current, but the average difference of motion is also greatest (with one exception) when the upper 
