158 THE BOOK OF FORESTRY 
quantities of water from the surface of the earth, the 
presence of large numbers of trees in a city has an 
appreciable effect during the heated term. The New 
York County Medical Society some years ago passed 
a resolution stating that ‘‘one of the most effective 
means of lessening the intense heat of the summer 
months and diminishing the death rate among chuil- 
dren is the cultivation of a sufficient number of trees 
on our city streets.”? Aside from their physical influ- 
ence which is hardly so great as is popularly believed, 
the presence of numerous small parks situated in the 
dense parts of the large cities has been found to actually 
diminish the number of criminal acts. Their quiet 
shade exerts a beneficial effect upon the overwrought 
nerves and in the words of the poet: 
There are green islands in the city sea, 
Where all day long the endless laboring waves 
Beat, yet destroy not and their quiet saves, 
How many a heart grown sick with memory. 
Trees and parks do far more than add to the beauty 
of a city. 
Just as the national park idea grew from the efforts 
of a few nature lovers, so has the city park and shade 
tree movement started from the efforts of public-spirited 
citizens who love green trees and worked for their pres- 
ervation within city limits. 
During the early nineties shade tree commissions were 
established in some of the Eastern cities and while their 
efforts lacked the directness and effect of later work, 
the real shade tree campaign in this country dates from 
about this time. Massachusetts, New Jersey and Penn- 
sylvania lead in tree and park work, and while as a 
nation we lag behind many foreign countries, a splendid 
