to the Firft Volume. 603

not therefore the defired effe&t, but rather made the matter worfe than before; for if a jutty is carried out at right angles, the current will be forced to the oppofite fide of the river, and thence it will rebound more violently than it did before. But if a jutty is placed obliquely, it will force the current gradually on the other fide, in which pofition one jutty may do more good than feveral placed improperly at right angles. He was therefore under the neceflity of making other jutties in this way, and has now the fatisfaction to find that they anfwer the purpofe intended. Thofe he made laterally formed a fort of convex flope, the convexity being parallel to the current. Strong planks were alfo firmly fet on edge among the ftones, their ends pointing towards the river; fo that if ever any current came fo rapid as to move any of the ftones, it muft move them all in a body the whole length of the plank. Perhaps this pre- caution was unneceflary; for although fiones are thrown into a river loofe in this manner, the flufh, fand,&c., that come down the river, will foon fill up all the cavi- ties, and render it as firm and folid as a regular built wall*,

“The next fort of embankments againft rivers are, it is obferved, thofe to prevent them overflowing their banks, and inundating large tracis of country. This may be confidered as the fipleft and eafieft of all forts of embanking if judicioufly ex. ecuted. It is therefore the more inexcufable to fee in fome places extenfive tracts of the richeft meadows completely overflown by every flood. Few ordinary-fized rivers rife more, even in the greateft floods, than five or fix feet above their common level, unlefs when they meet with fome confiderable interruption or confinement in their courfe. But if interrupted or confined, they will rife perhaps twenty feet ormore. If, forexample, a given quantity of water is fix fect deep when running over a{pace twenty feet wide, it is clear if that{pace were made only ten feet wide the water would rife to twelve feet; and if it were inade forty feet wide, the fame quan- tity of water would rife only to the height of three feet. It is therefore of great con- fequence, in preventing inundations, to give the river as much width as poffible, by widening every narrow place. All kinds of obftructions fhould alfo be removed, whether occafioned by windings, fhoals, tones, trees, buthes, or any thing elfe. In fome cafes this may even preclude the neceflity of embanking; but where embank- ing is neceffary, let the banks by all means be at a fufficient diftance from each other tocontain with eafe between them the largeft contents of the river in great floods. The diftance and height of the banks may eafily be afcertained by meafuring a fec- tion of the river when at its higheft, or when the flood-mark is vifible. Where. a fufficient diftance is allowed between the embankments, their height need not ex_

* Beatfon in Communications to the Board of Agriculture, Vol. II.