272 SEDIMENT OF THE PO. 



it annually transports to the shores of the Adriatic not less than 

 42,760,000 cubic metres, or very nearly 55,000,000 cubic yards, 

 which carries the coast-hne out into the sea at the rate of more 

 than 200 feet in a year.* The depth of the annual deposit is 

 stated at eighteen centimetres, or rather more than seven inches, 

 and it would cover an area of not much less than ninety square 

 miles with a layer of that thickness. The Adige, also, brings 

 every year to the Adriatic many million cubic yards of Alpine 

 detritus, and the contributions of the Brenta from the same source 

 are far from inconsiderable. The Adriatic, however, receives but 

 a small proportion of the soil and rock washed away from the 

 Itahan slope of the Alps and the northern decHvity of the Apen- 

 nines by torrents. Nearly the whole of the debris thus removed 

 from the southern face of the Alps between Monte Rosa and the 

 sources of the Adda — a length of watershed f not less than oug 

 hundred and fifty miles — ^is arrested by the still waters of the 



* This change of coast-line can not be ascribed to upheaval, for a compari- 

 son of the level of old buildings — as, for instance, the church of San Vitale 

 and the tomb of Theodoric at Ravenna— with that of the sea, tends to prove a 

 depression rather than an elevation of their foundations. 



A computation by a different method makes the deposits at the mouth of 

 the Po 2,123,000 metres less ; but as both of them omit the gravel and silt 

 carried down at ordinary and low water, we are safe in assuming the larger 

 quantity. 



f Sir John F. W. Herschel {Physical OeograpJiy, 137, and elsewhere) spells 

 this word water-sched, because he considers it a translation, or rather an adop- 

 tion, of the German " Wasser-scheide, separation of the waters, not waXer-shed 

 the slope doion icMcJi the waters run." As a point of historical etymology, it 

 is probable that the word in question was suggested to those who first used it 

 by the German WasserscJieide ; but the spelling icater-sched, proposed by Her- 

 schel, is objectionable, both because sell is a combination of letters wholly un- 

 known to modern English orthography and properly representing no sound 

 recognized in English orthoepy, and for the still better reason that water-shed, 

 in the sense of division-of-the-waters, has a legitimate English etymology. 



The Anglo-Saxon sceadan meant both to separate or divide, and to shade or 

 shelter. It is the root of the English verbs fa shed and to shade, and in the 

 former meaning is the A. S. equivalent of the German verb scheiden. 



Shed in Old English had the meaning to separate or distinguish. It is so 

 used in the Owl and the Nightingale, v. 197. Palsgrave {Lesclarcissement, etc., 

 p. 717) defines 1 shede, I departe thinges asonder ; and the word still means to 

 divide in several English local dialects. Hence, watershed, the division or sepa- 

 ration of the waters, is good English both in etymology and in spelling,— ^6« 

 a/rticle Watbbshed, in Johnston's Cyclopmdia. 



