88 



MR ROBERT COCKBURN MOSSMAN ON 



Hence the relative temperature of the winds has not appreciably changed during the 

 last 160 years. The results are very accordant except the direction of the warmest 

 point in Autumn, which was respectively E. from 1731-36, and N.E. from 1770-1776, 

 while it was S.W. from 1887 to 1894. I incline to the belief that the unusual warmth 

 of the sea winds during the earlier years is to be accounted for by the undue prevalence 

 of anti-cyclonic weather in these months. It is evident that when we are calculating 

 the mean temperature of a wind from a few values that the result will largely depend on 

 the type of weather which predominated during the time the wind in question prevailed. 



The number of observations tabulated in - the calculation of the windrose from 1731 

 to 1736 was 1,826, from 1770 to 1776, 2,557 were employed, while during the seven 

 years ending June 1894, 5,114 were utilised, so that it is evident that the latter average 

 gives the closest approximation. 



An inspection of the thermal windroses for the three periods will reveal many points 

 of similarity (see Plate IV.). 



Hygrometric Windrose [Table LIV.). 



The mean relative humidity of the winds has been already determined from the 

 9 a.m. and 9 p.m. readings of the dry and wet bulb thermometer for the seven years 

 ending June 1894. Values have been calculated for the five years 1731-36 with 

 a view of ascertaining whether any change has taken place in the humidity recorded 

 with the various winds. We cannot compare the actual means, but the following Table 

 showing the dampest and driest directions for the four seasons may be of interest : — 





Spring. 



Summer. 



Autumn. 



Winter. 



Dampest. 



Driest. 



Dampest. 



Driest. 



Dampest. 



Driest. 



Dampest. 



Driest. 



1731-36 

 1887-94 



E. 

 E. 



N.W. 

 ( N. W. 



In. 



N.E. 

 fN.E. 

 IE. 



S. 

 N.W. 



S.E. 



fN.E. 



E- 

 U-E. 



N.W. 



rs.w. 

 In.w. 



N.E. 



r 



(.S.E, 



N.W. 

 S.W. 



There has, therefore, been no change of any importance in the wind with which our 

 greatest and least humidities are experienced. Taking the mean annual values, the 

 dampest wind from 1731-36 was N.E., and the driest N.W., while during recent years 

 the points were E. and N.W. respectively. Sea winds were thus damp, and land winds 

 dry, a result entirely in accordance with recent observations (see Plate IV). 



General Results. 



An examination of the facts aj>parent from a comparison of the reduced values for 

 the five years 1731-1736 with observations taken during recent years, shows conclusively 

 that no appreciable alteration has taken place in the climate of the east of Scotland 



* Trans. Roy. Soc. Edin., vol. xxxviii. p. 751. 



