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greater elevation in the immediate neighbourhood ; and, in 
explanation of this remarkable fact, meteorological writers 
have generally adopted the hypothesis advanced by Professor 
Phillips (Report of the British Association for 1833, p. 410), 
“ that the whole difference in the quantity of rain at different 
heights above the surface of the neighbouring ground is 
caused by the continual augmentation of each drop of rain, 
from the commencement to the end of its descent, as it 
traverses successively the humid strata of air at a temperature 
so much lower than that of the surrounding medium, as to 
cause the deposition of moisture upon its surface.” In sup- 
port of this hypothesis, Professor Phillips remarks “ that it 
takes account of the length of descent, because in passing 
through more air more moisture would be gathered ; it agrees 
with the fact that the augmentation for given lengths of 
descent is greatest in the most humid seasons of the year ; 
it accounts to us for the greater absolute size of rain-drops 
in the hottest months and near the ground, as compared with 
those in the winter and on mountains ; finally, it is almost 
an inevitable consequence from what is known of the grada- 
tion of temperature in the atmosphere, that some effect of 
this kind must necessarily take place.” 
Now, although it must be admitted that the temperature 
of falling rain is generally below that of the air near the 
ground, yet if we proceed to determine the temperature of 
a rain-drop at the commencement of its descent, from its 
known rate of augmentation in falling, and from its tempera- 
ture when it arrives at the surface of the ground, we shall 
obtain a result wholly inconsistent with known facts, and 
therefore fatal to the hypothesis. 
The most complete series of observations with which I am 
acquainted, of the quantities of rain falling at difterent heights, 
is that made at York, in the years 1832-5, by Mr. Gray and 
Professor Phillips at the request of the British Association, 
the results of which are given and ably discussed by Professor 
