Prof. J. Brocklesby on the Influence of Color on Dew. 179 
one were made upon the latter. Four parcels of wool of differ- 
ent hues were provided—viz : gc dark © green, scarlet and 
January, the first, and the last two were exposed upon the leads 
of a house, and a few nights afterwards all the colors were sub- 
jected to the same exposure. The results were as follows : 
Grains. 
The Black gained 32 
First Experiment, Scarlet “ 25 
White “ 20 
The rick one “ 
Second Experiment, Dark 
Siig a 
m .* : White os 3 e 
These shvesttgarfon’ are considered by the author as. decisive 
of the point in queStion ; a and as establishing the fact, that dark 
and sombre hues are more favorable to the deposition of moisture, 
than those which are light and brilliant. 
deductions, however, appear to me iacamnd ais: for 
several reasons. First, because in this research the utmost deli- 
' cacy of investigation is ’ required, and it is almost, if not absolutely 
impossible, even with the nicest care, to guard against the op- 
ération of known causes, which, unless entirely excluded, will 
produce a perceptible difference in the results. 
Now we are not informed by Dr. Stark, either in respect to the 
uniformity of fibre in the wool employe , or as to the size of 
each parcel. A dissimilarity in either particular would cause a 
differen¢e in the amount of dew deposited. Moreover, on a sub- 
ae like os it is manifestly unphilosophieal to infer a generat 
law from 
With aid view of satisfying my own mind upon this point, I 
made, during the summer of 1846, a number of ne gg the 
details of which are presented in the following pa 
The material employed for the collection of mabistere was fine 
flannel. Having procured a white strip of an even texture, I cut 
it into six portions, and caused five to be dyed, each of a different 
ent color; viz., red (redwood), yellow (quercitron), green (fus- 
tic and indigo), blue (indigo), black (logwood). These six 
ir apparently all equally napped, were next cut to exactly 
same size, and weighed in a delicate balance. A want of 
dient | in weight was detected to the extent of a few ae 
This source of. error I endeavored to remove, by placing upon the 
far more numerous than those of Dr. Stark, and the voila he obtained sanmely 
PPpe 
regret hat I did not enjoy the pleasure of perme lfis highly instructive 
paper upon ‘this subject, until my experiments were clos 
