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towards the south, make the immediate shade trees nearer the mansion cooler. The 

 reason being that as most of our air currents and winds come from the south-west, even 

 a few more feet of shade in that direction give very marked coolness against the hot 

 currents of air from a sun-parched surface. And the question, therefore, must be logically 

 put, if a few trees make such marked difference in the temperature, what must be the 

 effect of great forests in the same direction upon animal comfort and plant growth 1 



Abstract of an interesting and valuable paper read at the Cincinnati meeting by 

 the Honourable Verplack Colvin, Superintendent of the New York State Adirondack 

 Survey : — 



The influence of forests upon the water supply of any given drainage area is directly 

 proportional to the rain-fall, and it is from the standpoint of evaporation and rain-fall 

 that the effect of forests must be considered. 



The data for the investigation must be searched for in the east, where the destruction 

 of forest has been great. Here, rather than on the frontiers of civilization, we should 

 look for traces of climatic change, if the destruction of forests lead to any such change. 



The records of the United States Signal Service of the mean monthly precipitation in 

 this country for many years had been searched by the lecturer for statistical information 

 on this subject, and he had based upon these records a series of computations which showed 

 where the greatest irregularities in the monthly rain-fall occurred. 



These differences were presented in tabular form, and showed a favourable uniform 

 monthly precipitation of rain in the Middle Eastern States. Here it is known that the 

 approximate limit of safety of forest-cutting has been reached, as torrential action began 

 to show itself in sections where much timber had been cut away. 



The topography of the country was shown to have a most important bearing upon the 

 quantity effect of forests upon the rain-fall; the mountain ranges, when forest-covered and 

 extending across the path of the south winds, acting as powerful condensers of moisture. 

 The way in which the limbs of trees entangle and kill the wind, to which a house or block 

 of houses forms hardly any obstacle, was explained in an interesting manner, and was 

 shown to be dependent on the angle of incidence. 



The true relationship of atmospheric electricity to rain-fall was traced through the 

 re-actions of the correlated force, so often incorrectly termed "latent heat." The limbs, 

 boughs and leaves of the forest were (when considered mechanically) natural machinery 

 most wonderfully adapted to the purpose of grasping upon the atmosphere, and thus caus- 

 ing those dynamic changes which induce the precipitation of moisture. 



The forests were, in fact, most singularly complicated condensers, and performed their 

 peculiar office in the atmosphere far better than the most skillfully contrived alembic of 

 the chemist. 



Forests were shown to be essential to a uniform rain-fall when existing in the proper 

 localities, as determined by the great local meteorological laws. 



A knowledge of the path of storms in any locality, and of the topography — the eleva- 

 tions and depressions, the rivers, marshes and lakes — was shown to be essential to any exact 

 estimate of the limit of .safety of the cutting of forests. The only way in which the wide- 

 spread knowledge necessary could be obtained would be by a general system of observation 

 by farmers and others throughout the whole country of the great facts of the local 

 rain-fall, direction of winds, etc., which could be easily done with little trouble. 



With these observations, and an accurate .system of topographical and forest maps 

 (which every State should have made), it would be possible to make close estimates as to 

 where forests must be preserved, where replanted and where they might be safely cut. 

 To secure this information required the intelligent co-operation of all citizens. The lec- 

 turer told of his personal experiences on the mountain peaks of the Adirondacks and 

 Rocky Mountains, and traced the origin of I'ain from its evaporation by the sun's rays 

 from the sea to its condensation to cloud — and showed how Buy Ballot's law readily en- 

 abled meteorologists knowing the path of storms, from a mere knowledge of the present 

 direction of the wind and the area of the last high or low pressure, to determine the prob- 

 able maximum or minimum liable to follow, and probable change in the direction of the 



