262

A TREATISE ON ROADS.

of the gauge. This section is taken through theline ef of fig. 8. In this figure the position of thesquare iron bolt, or screw pin, is more plainly seen,and also the washer placed under the thumb screw.Three of these bolts pass through the horizontalbar, fig. 8., exactly three inches above the line A C ;the other, seen at d, is only two inches above thesame line.

Levels for laying out slopes are best made of abar of wood, three inches deep, one inch thick, andsix feet long: on the centre near the middle of therod, a triangular piece of wood of the same thick-ness is nailed ; the sides of this triangular piece areso formed, that when the rod is placed upon a slopeof one to two or one to three, a small pocket levelplaced on one side of the triangle will be horizontal,and the bubble will remain in the centre.

Ring Gauges.

Ring gauges for ascertaining the size of thebroken stones are extremely useful. A ring ofthis description is represented in Plate VII. fig. 17*