26 Scientific Proceedings, Royal Dublin Society. 
Montruty AVERAGES ARRANGED IN ORDER oF RELATIVE 
Houmipiry. 
Relative Dew- Point Wind- Fall of 
Monti. Humidity at at Velocity, |Temperature, 
8 p.m. 8 p.m. 8-9 p.m. 8-9 p.m. 
Per cent. B M. per H. ‘ 
April, Prive votes 61 46°4 4-1 1:7 
June, 0 : ; 61 32°8 4-4 1-6 
July, Ry aed 58 32-4 3-9 1-9 
May, c : : 56 37°0 3°8 1:8 
March, : : : 50 47-5 4:7 2-2 
August, . 6 . 47 32°2 4:3 2-1 
September, . c ° 46 36°8 4-4 2°3 
February, . S : 43 48-8 4:8 2°0 
October, . ; : 40 36:9 5°6 2°3 
December, - j 5 37 44-1 6-1 2°4 
January, . : : 34 42°6 6°3 2°5 
November, - . 5 34 37°9 6:2 2°6 
It is evident from these tables that, so far as the present 
inquiry is concerned, the absolute and relative humidities are 
quite independent of each other. Nor is there any decided 
relationship between either and the velocity of the wind, although 
the latter is certainly highest in the summer, when the relative 
humidity is lowest. As toa relation between either and the fall 
of temperature, there cannot be any doubt, I think, that the 
relative humidity is the only element which shows it. As the 
air becomes drier the temperature falls faster, and at a rate 
which, for mnemonical purposes, may be represented by the 
formula 
6. H®. F*. = 100, 
where Z# is the relative humidity, and F, the fall of temperature 
in degrees Fahrenheit. A variation in the dew-point from 32° to 
49°, corresponding to a variation of vapour-tension of 18 inch to 
