c General Results of the Makerstoun Observations. 



Of the nine months in which the resultant wind is from between west and south, there are eight, for which it 

 occurs between W. 20° S., and W. 40° S., or nearly between WSW. and SW. ; in November the resultant 

 wind is most southerly, coming from W. 59° S. nearly SW by S. 



209. If we compare the mean of the pressures observed in all directions (last line of Table 90), in each 

 month, with the resultant mean pressure of the wind, the ratio will evidently give some measure of the varia- 

 bility of the wind ; where, by variability is meant the amount of opposedness of the masses of air in motion 

 during the period considered, without relation to the frequency of the oppositions ; the ratios are for each month as 

 follow : — 



Jan. 



Feb. 



Mar. 



April, 



May, 



June, 



July, 



Aug. 



Sep. 



Oct. 



Nov. 



Dec 



1-5 



3-1 



2-3 



4-6 



7-5 



2-0 



1-7 



2-& 



3-4 



2-2 



2-0 



1-6 



Of the whole amount of air in motion during each month, the greatest proportions proceed from one quadrant 

 or direction in December and January, the coldest period of the year, and also in July, the hottest month of 

 the year ; the winds are most equally distributed in all the quadrants in the months of April and May ; a 

 secondary maximum of variability occurring again in September. 



210. Diurnal Variation of the Resultant Mean Pressure of the Wind. — The following are the values of 

 the resultant mean pressure for each hour, as deduced from the observations for the years 1843-6 : — 



12'> \^ A.M. 2'' 3^ 4"^ b^ 6"^ 7'' Sh g*" 10'' \\^ <i^ l^ P.M. 2l> 3l» 4l> 6^ 6^ 7h gh Sh lOh lib 



lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. 

 0-15 015 016 0-17 0-17 017 0-16 0-16 0-21 0-23 025 0-25 0-25 0-27 0-2-1 0-21 0-19 0-18 015 0-15 0-15 0-15 0-15 0-16 



From these means the maximum occurs before l'^ p.m., and the minimum occurs between &^ p.m. and 1^ a.m. 



211. Diurnal Variation of the Direction of the Resultant Wind. — It was first pointed out in the volume 

 of Makerstoun Observations for 1843, p. 300, that the direction of the resultant wind had a diurnal variation, 

 being more towards the south of west in the morning and evening than about mid-day ; this result was con- 

 firmed with great distinctness in the discussion of the Observations for 1844 (vol. 1844, p. 438, and Plate 

 XVI.) ; an equally distinct result has been obtained from the observations for 1845 (p. 64 of this volume) ; 

 this has not been the case with the observations for 1846, a year which, when compared with the others, was ano- 

 malous in all its resultant directions (see No. 207). The following Table contains the means of the resultant 

 directions of each month for the years 1844 and 1845, and for the four years 1843-6, each year receiving an 

 equal value, and the means for the four years being obtained, as described No. 26. 



Table 96. — Diurnal Variation of the Direction of the Resultant Wind. 



Mak. 



Mean of 





Mak. 



Mean of 



Mean 









Mean 







Time. 



1844-5. 



1843-6. 



Time. 



1844-5. 



1843-6. 



h. 



o 





o 



h. 





o 



12 



W. 30 S. 



W. 



28 S. 







W. 15 S. 



W. 25 S. 



13 



W. 36 S. 



W. 



35 S. 



1 



W. 12 S. 



W. 24 S. 



14 



W. 34 S. 



w. 



34 S. 



2 



W. 9 S. 



W. 19 S. 



15 



W. 31 S. 



w. 



32 S. 



3 



W. 8 S. 



W. 17 S. 



16 



W. 35 S. 



w. 



36 S. 



4 



W. 16 S. 



W. 23 S. 



17 



W. 31 S. 



w. 



33 S. 



5 



W. 21 S. 



W. 26 S. 



18 



W. 30 S. 



w. 



30 S. 



6 



W. 22 S. 



W. 25 S. 



19 



W. 28 S. 



w. 



27 S. 



7 



W. 25 S. 



W. 27 S. 



20 



W. 18 S. 



w. 



22 S. 



8 



W. 39 S. 



W. 39 S. 



21 



W. 13 S. 



w. 



23 S. 



9 



W. 38 S. 



W. 35 S. 



22 



W. 10 S. 



w. 



19 S. 



10 



W. 38 S. 



W. 35 S. 



23 



W. 11 S. 



w. 



20 S. 



11 



W. 30 S. 



W. 28 S. 



The range of the variation for the four years 1843-6 is somewhat diminished by the anomalous numbers for 

 1846; but both series agree in shewing the resultant ^vind to be most westerly about 3^ p.m., and most 

 southerly between 8** p.m. and 4^ a.m. 



