



WHICH IS CONDENSED ON A COLD SURFACE. 303 
Next, let these values be substituted in the formula c=m(/”—/’”), which 
then becomes ¢=39°7 (‘27—-2)=2°779 grains. 
But as ¢ represents the weight of moisture which would be condensed on a 
surface of 100 square inches in 60 seconds, and we require to know the quantity 
which would be condensed on a surface equal to -00786 of a square inch in the 
lapse of three seconds, it will be necessary, in order to obtain this latter result, 
‘OO786 .. F which gives “000011 of a 
grain as the weight of moisture condensed on the surface of the rain-drop, while 
falling through 43:7 feet. 
Now, as the original weight of the drop was 0165 of a grain, it follows that 
the weight of moisture condensed on the drop was to the weight of the drop 
itself in the ratio of ‘000011 to ‘0165, that is, in the ratio of 00066 to 1. 
But, as was before shewn, the hypothesis assumes the ratio of these quanti- 
ties to be that of -42 to 1. 
Hence, unless there be some fallacy in the mode of arriving at the conclusion, 
to multiply 2°779 grains, the value of ¢, by 

the rate of condensation assumed by the hypothesis is aa = 635 times greater 
than the rate deduced from experiment. 
VOL. XX. PART II. 4N 
