364 APPENDIX 



culties of experimenting and even of making direct observations on the action of forests 

 bearing upon the feeding of springs, some light has necessarily been thrown on this 

 question from several directions. 



The different attempts which have been made have not all proved equally successful; 

 too great a number, especially those directed toward measuring directly the quantity of 

 water which passes through soil covered with varied vegetation, seem practically of 

 very little value. It does not concern us to discuss them here; we would only say that 

 all measurements and weighing performed in a laboratory can do nothing toward 

 solving the problem. 



It can only be solved by practical experiments on a large scale, and in the forests 

 themselves. To the "Station des recherches suisse" must be given the honor of having 

 inaugurated such an experiment, thanks to the initiative of its zealous director, Pro- 

 fessor Bourgeois. 12 



M. Bourgeois has chosen in the Emmenthal a fresh green valley in the hollow of the 

 northern buttresses of the Alps two little streams, the Rappengrabli and the Sperbel- 

 graben, 13 secondary affluents of the Emme, whose upper reservoirs could not be better 

 adapted to the researches he proposed to undertake. With an area of about 198 to 

 247 acres each they have the appearance of almost entire circles, very clearly defined 

 by a ridge in the form of a horseshoe. The general aspect of the thalweg (toward the 

 southeast) is identical as well as the nature of the soil and the altitude (which varies 

 from 3,215 to 4,035 feet in the case of the Rappengrabli, and from 2,953 to 3,937 feet 

 for the Sperbelgraben). The first is almost entirely composed of pasture land and has 

 only 18 per cent of forest disposed in a thin ribbon along the stream, in the thalweg; 

 the second (Sperbelgraben) is covered for 91 per cent of its extent with a splendid 

 irregular growth of fir. 



With the concurrence of the Federal hydrographies! office, a depositary has been 

 installed upon the two little streams, at the point where they issue from the almost 

 enclosed basins which constitute their upper valleys, permitting their outflow to be 

 measured with the utmost exactness. On the other hand rain gauges have been placed 



reported among the periodicals on forestry, especially hi the "Revue des Eaux et 

 ForSts" (see particularly the volumes for the years 1866, 1867, 1868). A Swiss en- 

 gineer, R. Lauterburg, quoted by M. Weber in the "Encyclopedic Forestiere de Lorcy," 

 asserts that the destruction of forests carried out in the canton of Tessin, principally 

 during the first half of the 1 9th century, must have reduced by a quarter the minimum 

 outflow of the Adige at the period of low water. A similar phenomenon has been 

 reported of the Po. Observations undertaken with the greatest care in Prussia by 

 M. G. Hagen (quoted by M. Lehr in the "Handbuch der Forstwissenschaft") seem to 

 prove conclusively that there has been a reduction in the total flow of nearly all the 

 rivers which have been observed (for instance the Elbe, Moselle, Vistula, Pregel, Memel) 

 in the course of the second half of the last century, but nothing proves that this phenome- 

 non is connected with the deforestation which was taking place at the same time. 

 M. Henry, a professor at the "Ecole National des Eaux et Forets," has also collected a 

 number of interesting and well-proved facts in a communication made in 1901 to the 

 "Societe" des Sciences de Nancy" under the title "Le Role des Forets dans les Circula- 

 tions des Eaux." "Le Journal Suisse d'Economie Forestiere" (1898) reports some 

 observations of M. de Rothenbach which prove, in a manner which appears to be con- 

 clusive, the influence of forests on the abundance of water in the springs which supply 

 the city of Berne, etc. 



12 The premature death of M. Bourgeois on the 8th September, 1901, has removed 

 one from whom the science of forestry had much to hope. He was under 46 

 years of age. His work in the Emmenthal is being carried on by his worthy suc- 

 cessor, Professor Egler; up till the present (July, 1903) no result of it has been 

 published. 



13 See Sheet No. 197 of the map of the "fitat-Major Suisse " at 1/25,000. The experi- 

 ments took place about 21.1 miles east (airline) of Berne in the canton of the same name, 

 47!' north latitude and 532 (about) east longitude (of Paris). 



