FORESTS RETAIN MOISTURE. 147 



become, one of them a little trickling rill, which I could step 

 across, and the other a series of mud-holes. The difficulty 

 was, that the forests, the sources of those streams, had been 

 cut down. The rain which falls in a forest penetrates the 

 earth, which, protected by the roots of the trees, keeps a 

 portion of it there for the whole year. Thus in a forest the 

 water is laid up, kept as though it were a treasure, and it con- 

 tinues to trickle away from that forest every day in the 

 year. Cut down the trees, and all the rain that falls in 

 the spring, all the water that is produced by the melting of 

 the snow of winter, pours down in great floods. It was the 

 great floods that carried away those mills and those dams. 

 They all come down at once, and there is nothing left. But 

 that is not the only loss. Where the trees have been cut down, 

 the leaves, and that substance made of leaves, the most 

 valuable of manures, are dried up, and the first flood carries 

 this oflf; next after that, the earth that has been formed by 

 the leaves ; and after that is gone, the fine sand ; then the 

 coarse sand. Having watched the operation of these causes 

 in our little rivers, I went to Europe some years ago, for the 

 purpose of studying that among other things ; and I found, 

 in the south of France and the north of Italy, hundreds of 

 thousands of acres where exactly this process had taken place. 

 A poor man living on the branch of the Po, for example (and 

 this process had been going on longer and more terribly on 

 the Po than any other river known), having a little farm, 

 and wanting some wood to burn, or to send to market, cuts, 

 down his trees. 



Apparently, he has done no harm ; but the winter's snow 

 and the spring rains come, and as I have said, the leaves 

 having been dried up, the next rains carry their- substance 

 away, and gradually the increasing torrents carry heavier and 

 heavier substances, until, at last, on the steep sides of hills, 

 they carry ofi" great stones. This destruction has been going 

 on for hundreds of years in the valley of the Po. The Po, 

 when first spoken of in history, was a charming river from 

 its innumerable sources in the Alps on the north side, and 

 the Appenines on the south side ; one of the most charming 

 rivers in the world, and a blessing to all who dwelt on its 

 banks. Its channel is now filled up. It has extended its 



