Apeil 10, 1896.] 



SCIENCE. 



551 



growth has sprung i>p much thicker, and 

 none of the young trees will start until the 

 old ones are gone. Another is that the 

 water supply from the mountains is greater 

 and more permanent now than it was before 

 the timber was cut off. The reason for this 

 is that the wind has a more unimpeded 

 course, and as all the snow storms come 

 from nearly the same point in the south 

 the snow is blown over and lodges on the 

 north sides of the ridges where it is piled 

 deep in drifts, and not being exposed 

 directly to the sun's rays it melts very 

 slowly and thus affords a more permanent 

 supply. Spring floods are less frequent and 

 for the same reason. I do not pretend to 

 decide how much, if any, the presence of 

 trees induce precipitation. They may 

 moisten the air, but the humidity is all 

 taken out of the ground hj the roots, and I 

 observe that the undergrowth and grass is 

 more luxuriant since the timber was cut 

 off." 



It is hardly necessary to point out 

 the advantage of having the snow sup- 

 ply heaped up in large drifts or buried deep 

 in the canyons rather than to have it 

 spread out, exposing large surfaces to the 

 sun and the dry air, which in such places 

 is almost constantly in motion, thus multi- 

 plying its capacity. In drifts the melting is 

 almost all done at the bottom, and far into 

 the summer a little rill will be found running 

 away from the lower side. Good sized 

 caves are often formed in this manner, and 

 sometimes the top crust is so solid that the 

 last seen of a big drift will be an arched 

 shell of frozen snow reaching from one wall 

 of the canyon to the other. The beautiful 

 adaptation of the means to the end seen 

 everywhere in nature is illustrated here. 

 To attempt to hold back an adequate sup- 

 ply of water for a great region like that Ij^- 

 ing below the Sierra Nevada range in any 

 except a solid state would be utterly use- 

 less. Nothing in a liquid form would tarry 



long on a heavy grade. No shade nor mat 

 of leaves would be strong enough to over- 

 come the law of gravitation to that extent. 

 Nothing could detain it but a short time at 

 the farthest, and if it were not for the vast 

 drifts which hold the snow in an icy grasp 

 until late in the summer, all the horrors 

 prophesied from spring floods and summer 

 droughts would be realized. As it is, I notice 

 that heavy storms continue to visit the places 

 from which the timber has been taken, but 

 when an unfavorable season fails to bank 

 up the drifts there is no water in the 

 streams whether there are trees or stumps 

 on the ground. There are places in Ne- 

 vada which would give a strong support to 

 the theory that the cutting oS" of timber 

 brings frequent floods, if any had ever 

 been there, for since the settlement of the 

 country there have been several terrible 

 floods which have been given the name of 

 cloudbursts on account of the suddenness 

 of the rise and subsidence of the water. 

 The town of Austin, Nevada, is a sample. 

 It has been swept several times by sudden 

 floods, and as it lies in a narrow canyon 

 which opens out above and spreads into 

 quite a watershed, it is in constant danger. 

 There never was a forest there and in early 

 days there were no cloudbursts, but the dis- 

 covery of rich mines led to the whole basin 

 being tramped over and over constantly 

 until the ground was as hard as a pavement. 

 The result was that rains which formerly 

 were taken into the soil ran down the 

 waterways into the main canyon, which 

 soon collected a roaring torrent and swept 

 everything out. In so large a subject there 

 are many things to consider and many un- 

 known quantities to discover and weigh, 

 but it seems to me that it is worthy of more 

 attention than it has received. My ob- 

 servations, while they have extended over 

 a long series of years, have been those of a 

 layman and have not been such as to afford 

 mathematical proof, even that a given 



