SIR: The letter to which you do me the honor to refer, in your yesterday's article on the Tiber, entered into no detail,[106] because I had already laid the plans spoken of before the Royal Institution in my lecture there last February;[107] in which my principal object was to state the causes of the incalculably destructive inundations of the Rhone, Toccia, and Ticino, in 1868; and to point out that no mountain river ever was or can be successfully embanked in the valleys; but that the rainfall must be arrested on the high and softly rounded hill surfaces, before it reaches any ravine in which its force can be concentrated. Every mountain farm ought to have a dike about two feet high--with a small ditch within it--carried at intervals in regular, scarcely perceptible incline across its fields; with discharge into a reservoir large enough to contain a week's maximum rainfall on the area of that farm in the stormiest weather-the higher uncultivated land being guarded over larger spaces with bolder embankments. No drop of water that had once touched hill ground ought ever to reach the plains till it was wanted there: and the maintenance of the bank and reservoir, once built, on any farm, would not cost more than the keeping up of its cattle-sheds against chance of whirlwind and snow. The first construction of the work would be costly enough; and, say the Economists, "would not pay." I never heard of any National Defences that did! Presumably, we shall have to pay more income-tax next year, without hope of any dividend on the disbursement. Nay--you must usually wait a year or two before you get paid for any great work, even when the gain is secure. The fortifications of Paris did not pay, till very lately; they are doubtless returning cent. per cent. now, since the kind of rain falls heavy within them which they were meant to catch. Our experimental embankments against (perhaps too economically cheap) shot at Shoeburyness are property which we can only safely "realize" under similarly favorable conditions. But my low embankments would not depend for their utility on the advent of a hypothetical foe, but would have to contend with an instant and inevitable one; yet with one who is only an adversary if unresisted; who, resisted, becomes a faithful friend--a lavish benefactor. Give me the old bayonets in the Tower, if I can't have anything so good as spades; and a few regiments of "volunteers" with good Engineer officers over them, and, in three years' time, an Inundation of Tiber, at least, shall be Impossible. I am, Sir, your faithful servant, JOHN RUSKIN. DENMARK HILL, _Jan._ 19, 1871. FOOTNOTES: [106] The _Pall Mall Gazette_ had quoted part of the preceding letter, and had spoken of "a remedy which Mr. Ruskin himself appears to contemplate, though he describes it in rather a nebulous manner."