58 
GREELY. 
the good reason that they have apparently not recognized 
the source whence comes the rain. 
Even over a very extensive range of latitude the rainfall 
regime is sometimes, as in the case of California, so thor¬ 
oughly similar that a composite curve can be drawn which 
will outline with general accuracy both the definite distribu¬ 
tion throughout the year and the proportionate amounts 
pertaining to individual months. In Texas, however, a 
single composite curve, formed from observations represent¬ 
ative of ail sections of the State, would convey misleading 
and incorrect ideas for the greater part of the whole area. 
Only a cursory consideration of the rainfall data is essen¬ 
tial to be assured, as one would surmise from theoretical 
considerations concerning so vast a region as Texas, that no 
single type of distribution throughout the year applies to 
the whole State. 
Instead of one or two composite curves, it was necessary 
in this case to reproduce quite a number of a representative 
character, based on the average daily rainfall (in hundredths 
of an inch) at suitable separate points in or adjacent to Texas. 
These curves, derived from a long series of observations by 
observers of the Signal Corps at each station, graphically 
represent the mean rainfall distribution characteristic of 
the station in question and of the country adjacent thereto. 
Only three of these curves are here presented. 
If the annual rain fell regularly throughout the year it is 
evident that 8.3 per centum would fall each month. I have 
elsewhere designated as a dry month one in which the pre¬ 
cipitation is not equal to 4.2 per centum, and a very dry 
month one in which the rain was not equal to 2.1 per centum 
of the annual precipitation. In like manner, a wet month 
has from 13 to 16 per centum, and a very wet month more 
than 17 per centum of the rain for the entire year. Under 
this scale July and August are, relatively speaking, very wet 
months for the Trans-Pecos region, while December and 
January are very dry months through all western Texas. 
Along the Gulf coast September is also a wet month. 
