AND FENC ES. 11

dike, it at once affumes the pofition as marked at BAC, and thus allows the op- pofite fide-band O to join quite clofely to

it; whereas, had it not got the rut at B

(Fig. 4th.) it would have projected out- ward above, as at D; fo that the feal O could not have joined it clofely, but would have left a triangular opening in the heart of the dyke, as marked in the two courfes of feal below this, which would make the dike far lefs folid and compact than it is when managed in this way. Tn this manner the workmen proceed, always rutting the through-band rows of feal in both ends, but the fide-bands only on one fide, beginning every courfe with thofe which go acrofs the dike; fo that if the meafures are taken exactly, and the whole be rutted by the line, they may work with the utmoft freedom, and every feal will join to the others at the firft with the utmoft accuracy and facility.“The upper- moft courfe of feal is cut a little longer than thofe that are immediately below it, and placed with the grafly fide uppermott,

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