Towards the rear of the house, on the west side, he came across a curious abutment of masonry jutting out squarely from the wall.

The abutments on either side of the Straits are huge piles of masonry.

The swing bridge extends over two openings, or from the north abutment to the southern pier, its center of revolution being situated over the center of the northern span, and revolves upon a turntable, which is carried upon a lower platform or frame of girders extending across the northern span of the bridge.

The abrupt rise, which is feared from firm circular arches, may be easily prevented, by a little extension of the abutment at each end, which will take away the objection, and add almost nothing to the expense.

This forms an abutment for supporting the ladle in the gudgeon band, being secured to this last by latch bolts and cotters.

An arch consists of a series of wedge shaped blocks, known as voussoirs, arranged in a curve, and so locking one another together that unless the abutments from which the arch springs give way, it will not only carry itself, but sustain a heavy load.