INFLUENCE OF THE FOREST ON SPRINGS. 
205 
entirely stripped of their wood, chiefly to furnish fuel for salt¬ 
works. Our author adds that other cases, similar to those 
already detailed, might be cited, and he proceeds to show, by 
several examples, that the waters of other lakes in the same 
regions, where the valleys had always been bare of wood, or 
where the forests had not been disturbed, had undergone no 
change of level. 
Boussingault further maintains that the lakes of Switzer¬ 
land have sustained a depression of level since the too prevalent 
destruction of the woods, and arrives at the general conclusion, 
that, “ in countries where great clearings have been made, 
there has most probably been a diminution in the living waters 
which flow upon the surface of the ground.” This conclusion 
he further supports by two examples: one, where a fine spring, 
at the foot of a wooded mountain in the Island of Ascension, 
dried up when the mountain was cleared, but reappeared when 
the wood was replanted; the other at Marmato, in the province 
of Popayan, where the streams employed to drive machinery 
were much diminished in volume, within two years after the 
clearing of the heights from which they derived their supplies. 
This latter is an interesting case, because, although the rain 
gauges, established as soon as the decrease of water began to 
excite alarm, showed a greater fall of rain for the second year 
of observation than the first, yet there was no appreciable 
increase in the flow of the mill streams. From these cases, the 
distinguished physicist infers that very restricted local clear¬ 
ings may diminish and even suppress springs and brooks, 
without any reduction in the total quantity of rain. 
It will have been noticed that these observations, with the 
exception of the last two cases, do not bear directly upon the 
question of the diminution of springs by clearings, but they 
logically infer it from the subsidence of the natural reservoirs 
which springs once filled. There is, however, no want of posi¬ 
tive evidence on this subject. 
Marschand cites the following instances : “ Before the fell¬ 
ing of the woods, within the last few years, in the valley of the 
Soulce, the Combe-^s-Mounin and the Little Valley, the Some 
