cii General Results of the Makeestoun Observations. 



214. Sums of the Pressures with which the Wind blew from each of the 16 Principal Poi)its of the Com- 

 pass. — Following the same procedure as in No. 213, we obtain the following sums of pressure from four years' 

 observations, of 24 a-day, the sums being of the maximum pressures observed within 10«i at the hours of obser- 

 vation. (See No. 198.) • 



N. 



NNE. 



NE. 



ENE. 



E. 



ESE. 



SE. 



SSE. 



s. 



ssw. 



SW. 



wsw. 



w. 



WNW. 



NW. 



NNW. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



711 



757 



722 



442 



217 



84 



163 



362 



749 



1945 



3411 



1262 



990 



693 



689 



654 



The sums of pressures obey nearly the same laws as the frequency mth which the wind blew ; the greatest sum 

 of pressures occurred a few degrees south of S W. ; the sum then diminishes to W. , varies little from WNW. to 

 N. being, on the whole, less at NNW. than for the adjacent points ; it becomes a secondary maximum about 

 NE; by N., a principal minimum at ESE. (See curve a in the figure, p. ci.) 



215. Mean Pressure with which the Wind blew from each of the 16 Principal Points of the Compass. — Di- 

 viding the sums of pressures for each of these points (No. 214) by the number of observations for which the 

 wind was observed blowing at 01 lb., or upwards (No. 213), we obtain the following mean pressures with which 

 the wind blew from each of the 1 6 points : — 



N. 



NNE. 



NE. 



ENE. 



E. 



ESE. 



SE. 



SSE. 



s. 



SSW. 



sw. 



wsw. 



w. 



WNW. 



NW. 



NNW. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



lb. 



0-91 



0-57 



0-43 



0-51 



0-50 



0-47 



0-50 



0-63 



0-69 



0-73 



0-81 



0-65 



0-82 



0-95 



0-74 



0-75 



The Avind blew vsdth the greatest force from WNW. and N., and with the least force from NE. and ESE., 

 but the mean force was nearly constant between NE. and SE. The mean force with which the wind blew be- 

 tween NNE. and SSE. = 0-52 lb., between NNW. and SSW. = 0-78 lb., or in the ratio of 2 to 3. "VMien 

 the projection of the previous values upon tJie directional radii are connected, a very sjTnmetrical figure is 

 formed, having three minima at intervals of about 80°, namely, at NE., NW by N., and WSW. (See curve 

 c in the figure, p. ci.) 



Motions of Different Currents of Air. 



216. Difference of the Directions of Motion of the Upper and Lower Currents of Air. — The mode in which 

 the directions of motion of the clouds were observed is described in the introductions to the previous, volumes 

 in the section, " State of the Sky.'' The process by which the results for the difierences of motion of the dif- 

 ferent currents were obtained by the combination of simultaneous observations, will be found stated in the 

 volume for 1844, p. 440. The detailed results for each of the four years 1843-6 are given in separate tables in 

 the present and in the previous volumes. The total number of comparisons of the currents of scud, cirro-stratus, 

 and cirrus, with the surface-current, and of the cirro-stratous and cirrous-currents with the scud-current, was in 

 1843, 865 ; the numbers of results (each of fr-om five to two comparisons) were in 1844, 995 ; in 1845, 964 ; 

 and in 1846, 541. In the discussion for 1843 only one or two simultaneous obsers-ations were termed a com- 

 parison ; from five to two simultaneous observations were termed a result for the three following years (see 1844, 

 p. 440) ; but as the values of the final results for each year were not considered greatly different, the numbers 

 of comparisons of 1843, diminished by a tenth, have received the weight of the results in the following years, 

 and the numbers of results for 1846 were increased by a half in the combinations given below. The weights 

 of the four years 1843, 1844, 1845, and 1846, were taken on the whole, therefore, as 779 : 995 : 964 : 811. 



217. The scud-current includes the cumulus ; the cirro-stratous current includes also the cloud termed in the 

 Makerstoun Observations the cirro-cmnulo- stratus : this cloud, so frequently seen, has received no name in 

 Mr Howard's classification ; it belongs to the region of the cirro-strati, and is composed of great numbers of 

 clouds like small cirro-strati, arranged with a cirro-cumulous disposition. After this name had been applied to 

 this cloud for some time, I discovered that Mr Howard had given it already to the Nimbus. The cirrous 

 current includes the cirro-cumulus. The order of reckoning being from north, by the east, south, and west, 

 one current is considered positive of another when it proceeds from a point more southerly in the eastern semi- 

 circle and more northerly in the western semi-circle. 



218. AVlien we consider the results for each quadrant, we find they present difierences, both in the values 

 and signs of the mean differences of the directions of motion ; in three of the quadrants, however, namely E to 

 S., S to W., and W to N., the signs are the same ; in every case the mean upper curi'ents proceed from points 

 positive of the currents below them. In the quadrant S to W. by far the greatest number of results have 

 been obtained, and they are by far the most regular and distinct. Thus, in 774 results, each obtained from several 

 comparisons of the current of scud with the surface-wind, 664 shewed the scud-current to proceed from a point 



