88 
A discussion arose in regard to the apparent changes in the 
dryness of the climate, and the causes which had led thereto, 
between Messrs. Collingwood, Morris, Stevenson, and the 
Chairman. Particular reference was made to the removal of 
timber, as causing, not indeed an actual lessening of annual 
rainfall, but an effect similar in its results, viz.; the loss of 
all the spring rain and snow-water, in freshets, etc., and a re- 
suliing summer drouth. The Chairman stated that one im- 
portant agency in this injury, is the clearing out of the 
streams on hills and mountain-sides, to serve as timber-shutes. 
In a state of nature, the flow of water in the streams is greatly 
slackened and checked by the accumulations of fallen logs, 
and other forest debris; and thus the spring freshets of a 
river are largely reduced, by these impediments to a free and 
rapid flow in all the little tributaries. But when these small 
streams are used to float down timber, the Jumbermen clear 
away every such obstacle; and the consequence is that with 
each spring rain, the water rushes down unchecked, creates 
a flood fora day or two in the country below, and is then 
lost to further use. All along the Alleghanies of Pennsyl- 
vania this ruinous process has been, and still is, going on, as 
he had lately learned from gentlemen of intelligence living 
in those regions; and: here is seen another danger growing 
out of our reckless tampering with nature. 
Pror. Oscar LOEW gave a brief account of his observa- 
tions, while travelling during the past summer with the War 
Department survey, in portions of New Mexico and Arizona, 
and referred particularly to the richness of the latter territory, 
in its south-western part, in copper mines. 
Pror. J. J. STEVENSON gave an outline of the course 
pursued by Col. Wheeler’s party, to which he was attached, 
in southern Colorado. 
