2°96 INFLUENCE OF THE FOREST ON SPRINGS. 
“The influence of the forest on springs,” says Hummel, “ is 
strikingly shown by an instance at Heilbronn. The woods on 
the hills surrounding the town are cut in regular succession 
every twentieth year. As the annual cuttings approach a cer- 
tain point, the springs yield less water, some of them none at 
all; but as the young growth shoots up, they flow more and 
more freely, and at length bubble up again in all their original 
abundance.” * 
Dr. Piper states the following case: “ Within about half a 
nile of my residence there is a pond upon which mills have been 
standing for a long time, dating back, I believe, to the first 
settlement of the town. These have been kept in constant 
operation until within some twenty or thirty years, when the 
supply of water began to fail. The pond owes its existence to 
a stream that has its source in the hills which stretch some 
miles to the south. Within the time mentioned, these hills, 
which were clothed with a dense forest, have been almost en- 
tirely stripped of trees; and to the wonder and loss of the mill- 
owners, the water in the pond has failed, except in the season 
of freshets; and, what was never heard of before, the stream 
itself has been entirely dry. Within the last ten years a new 
growth of wood has sprung up on most of the land formerly 
oceupied by the old forest; and now the water runs through 
the year, notwithstanding the great droughts of the last few 
years, going back from 1856.” 
Dr. Piper quotes from a letter of William C. Bryant the 
following remarks: “ It is a common observation that our sum- 
mers are becoming drier and our streams smaller. Take the 
Cuyahoga asan illustration. Iifty years ago large barges loaded 
with goods went up and down that river, and one of the vessels 
engaged in the battle of Lake Erie, in which the gallant 
Perry was victorious, was built at Old Portage, six miles north 
of Albion, and floated down to the lake. Now, in an ordinary 
stage of the water, a canoe or skiff can hardly pass down the 
stream. Many a boat of fifty tons burden has been built and 
* Physische Geographie, p. 32. 
