ROZET’S PLAN. _ 513 
to place along one or both banks, according to circumstances, a 
line of cubical blocks of stone or pillars of masonry three or 
four feet high and wide, and at the distance of about eleven 
yards from each other. The space between the two lines, or 
between a line and the opposite high bank, would, of course, 
be determined by observation of the width of the swift-water 
current at high floods. As an auxiliary measure, small ditches 
and banks, or low walls of pebbles, should be constructed from 
the line of blocks across the grounds to be protected, nearly at 
right angles to the current, but slightly inclining downwards, 
and at convenient distances from each other. Rozet thinks the 
proper interval would be 300 yards, and it is evident that, if he 
is right in his main principle, hedges, rows of trees, or even 
common fences, would in many cases answer as good a purpose 
as banks and trenches or low walls. The blocks or pillars of 
stone would, he contends, check the lateral currents so as to 
compel them to let fall all their pebbles and gravel in the main 
channel—where they would be rolled along until ground down 
to sand or silt—and the transverse obstructions would detain 
the water upon the soil long enough to secure the deposit of its 
fertilizing slime. Numerous facts are cited in support of the 
author’s views, and I imagine there are few residents of rural 
districts whose own observation will not furnish testimony con- 
firmatory of their soundness.* 
* The effect of trees and other detached obstructions in checking the flow 
of water is particularly noticed by Palissy in his essay on Waters und Foun- 
tains, p. 175, edition of 1844. ‘‘ There be,” says he, ‘‘in divers parts of 
France, and specially at Nantes, wooden bridges, where, to break the force of 
the waters and of the floating ice, which might endamage the piers of the 
said bridges, they have driven upright timbers into the bed of the rivers above 
the said piers, without the which they should abide but little. And in like 
wise, the trees which be planted along the mountains do much deaden the 
violence of the waters that flow from them.” 
Lombardini attaches great importance to the planting of rows of trees trans- 
versely to the current on grounds subject to overflow.—Hsame degli Studi sul 
Tevere, § 53, oe Appendice, $$ 33, 34, 
o 
