226 INFLUENCE OF THE FOEEST ON SPEINGS. 



Of the converse proposition, namely, that the planting of new 

 forests gives rise to new springs and restores the regular flow of 

 rivers, I find less of positive proof, however probable it may be 

 that such effects would follow.* A reason for the want of evi- 



natural soil of the prairies, has furnished a reservoir for the rains which are 

 absorbed by the earth and carried gradually to the river by subterranean flow, 

 instead of running off rapidly from the surface, or, as is more probable, instead 

 of evaporating or being taken up by the vigorous herbaceous vegetation which 

 covers the natural prairie. 



A phenomenon so contrary to common experience, as would be a permanent 

 increase in the waters of a great river, will not be accepted without the most 

 convincing proofs. The present greater facility of navigation may be attrib- 

 uted to improvements in the model of the boats, to the removing of sand- 

 banks and other impediments to the flow of the waters, or to the confining of 

 these waters in a narrower channel by extending the embankments of the 

 river, or to yet other causes. 



So remarkable a change could not have escaped the notice of Humphreys 

 and Abbott, whose most able labors comprise the years 1850-1861, had it 

 occuiTed during that period or at any former time within the knowledge of 

 the many observers they consulted ; but no such fact is noticed in their 

 exhaustive report. However, even if an increase in the volume of the Missis- 

 sippi, for a period of ten or twenty years, were certain, it would still be 

 premature to consider this increase as normal and constant, since it might 

 very well be produced by causes yet unknown and analogous to those which 

 influence the mysterious advance and retreat of those Alpine ice-rivers, the 

 glaciers. Among such causes, we may suppose a long series of rainy seasons 

 in regions where important tributaries have their far-off and almost unknown 

 sources ; and with no less probability, we may conceive of the opening of 

 communications with great subterranean reservoirs, which may from year to 

 year empty large quantities of water into the bed of the stream ; or the closing 

 up of orifices through which a considerable portion of the water of the river 

 once made its way for the supply of such reservoirs. — See upon this point, 

 Chap. IV., Of Subterranean Waters; post. 



* According to the Report of the Department of Agriculture for February, 

 1873, it is thought in the Far West that the young plantations have already 

 influenced the watercourses in that region, and it is alleged that ancient river- 

 beds, never known to contain water since the settlement of the country, have 

 begun to flow since these plantations were commenced. See also Hayden, 

 Report on Oeological Survey of Wyoming, 1870, pp. 104 and 455 ; also Hay- 

 den, U. S. Survey of Colorado for 1874, p. 2G5 ; and Bryant, Forest Trees, 

 1871, chap. iv. 



In the Voyage autour du Monde of the Comte de Beau voir, chap, x., this 

 passage occurs : Dr. MilUer, Director of the Botanic Garden at Melbourne, 

 " has distributed through the interior of Australia millions of seedling trees 

 from his nurseries. Small rivulets are soon formed under the young wood ; 

 the results are superb, and the observation of every successive year confirm* 



