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.m ; the sums resolved in the W. attain their maximum 

 earliest, about Noon ; wliile the sums resolved in N. and in S. attain their maximum about l'^ p.m. The re- 

 sultant sums of pressures attain their maximum about 0^ 30™ p.m., minima occur about 7*^ a.m. and &^ p.m. 

 The mean resultant attains a maximum about Noon, the minimum occurs about 2>^ 40™ p.m. ; the maximum 

 probably occurs near midnight, a secondary minimum occurs about 1^ 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. 



Currents. 



Quadrant N. to E. 



Quadrant E. to S. 



Quadrant S. to W. 



Quadrant W. to N. 



No. of 

 Obs. 



Difis. of 

 Motion. 



jfean 

 Diff. 



No. of 

 Obs. 



DiffsJ of 

 Motion. 



Mean 

 Diff. 



No. of 

 Obs. 



Diffs. of 



Motion. 



Mean 

 Diff. 



No. of 

 Obs. 



Diffs. of 

 Motion. 



Mean 

 Diff. 











O 





o 









o 



o 









o 



Scud minus J 

 Wind 1 



75 

 30 



+ 27-9 

 -44-2 



+ 7-4 



22 



7 



+ 29-3 

 - 530 



+ 9-5 



177 



20 



+ 23-7 

 -22-6 



+ 19-0 



44 

 18 



+ 18-5 

 -32-3 



+ 3-7 



Cir.-str. minus) 

 Wind 1 



15 

 14 



+ 48-3 

 -55-7 



- 1-9 



12 

 2 



+ 500 

 - 67-5 



+ 33-2 



87 

 12 



+ 47-6 

 -23-7 



+ 35-4 



23 

 12 



+ 26-8 

 -46-6 



+ 17 



Cir.-str. minus) 

 Scud 1 



14 

 9 



+ 41-8 

 -50-6 



+ 5-6 



7 

 2 



+ 11-9 

 - 25-3 



+ 3-6 



57 

 14 



+ 34-5 

 -19-7 



+ 23-9 



28 

 19 



+ 20-3 

 -50-7 



- 8-4 



Cirri minus ) 

 Wind 1 



8 

 6 



+ 66-4 

 -57-2 



+ 13-4 



3 

 



+ 82-5 



+ 82-5 



42 

 7 



22 

 5 



+ 46-7 

 — 38-fi 



+ 34-5 



10 

 5 



+ 23-9 

 -50-6 



- 1-0 



Cirri mimis ) 

 Scud 1 



7 

 2 



+ 33-7 

 -25-0 



+ 21-3 



1 

 1 



+ 67-5 

 -157-5 



-45-0 



+ 32-7 

 -35-6 



+ 20-1 



16 



8 



+ 19-8 

 -87-2 



-159 



This Table has been formed by taking the diifei-ences 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, fi-om N. to E., S. 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 diftei'ence of the motions from aZ^ 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 all 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 

 diflerence (with two exceptions) is'greater for the minus than for the positive observations. In the quadrant S. 

 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 



