270 J. ARTHUR HARRIS AND JOHN V. LAWRENCE 
and distribution. Thus Shreve (1914), in working through the records 
which have been kept at Cinchona for the past thirty-nine years, 
finds variation in the total annual precipitation from about 59 to 
about 179 inches. In October, the rainfall has varied from about 
3 to 43 inches. In February, precipitation has ranged from less 
than an inch to nearly 13 inches. At New Haven Gap during the 
three months of April, May and June, 1892, there was not a measur- 
able amount of rainfall, whereas during the same three months in 
1894 there fell 62 inches of water. 
Thus the vegetation is by no means free from occasional periods 
of drought. 
Notwithstanding this fact, moisture is so great in quantity and 
so uniform in distribution that it supports a dense evergreen arbores- 
cent and herbaceous vegetation, a large proportion of the constituent 
species of which are of a pronouncedly hygrophilous character. As 
a factor in the development and maintenance of the vegetation, the 
distribution as well as the actual quantity of the precipitation is a 
factor of great importance. Precipitation is almost exclusively in 
the form of light showers of brief duration or gentle and long con- 
tinued rain, but never in the torrential downpours so characteristic 
of deserts and tropical lowlands. Transient showers of too brief 
duration to be registered as giving a measurable quantity of rainfall 
are frequent. Shreve gives a table showing that at Cinchona on an 
average from one third to two thirds of the days of the twelve indi- 
vidual months of the year have a measurable precipitation. 
On the northern slopes fog is prevalent from below 4,500 feet to 
the summits of the highest peaks from 10 a. m. to 4 p. m. on a large 
proportion of the days during all the months of the year, with the 
possible exceptions of July and August. Fog is much less frequent 
on the southern exposure of the mountains, but even here it is often 
seen on the upper slopes, and a large percentage of the days are cloudy 
or partially cloudy. Shreve, after nearly a year's residence in the 
Blue Mountains, describes the condition as follows: "The typical 
course of the day's weather is: clear from sunrise until 9 to 11 a. m., 
intermittently or entirely cloudy until nearly sunset, with two or 
three hours of fog in the mid-day or early afternoon, the sun setting 
clear. Rain usually occurs in the mid-day or early afternoon and 
the night is clear." 
As a consequence of the high and well-distributed rainfall and 
