Chap. XIV.

ON PILES AND PILE-DRIVING.

I0S1

in the groove, in such manner as the saw is required to move, and this motion constitutesthe value of the machine.

A lever bent into three different directions, moving on a pivot at the first angle of itsbending, and having a movable roller at the other, conveys the motion from the bascule orsee-saw directly to the saw : the dotted lines show the extent of this motion one way, andthe shaded part that of the other.

Fig. 1654.

DE CESSART’S TILE-CUTTER.

In the section we see the various positions of the bascule or jointed rods when thesawing is in progress. The two wheels shown in the plan are worked by a rack and pinionby means of a rod coming from the top, by turning which any required pressure is givento the saw. The grapples, which clutch the head of the piles, are drawn back by means oflevers worked at the top, and they are kept from turning by a rope attached to a ringfastened to one of the timbers of the upper platform : the time for cutting off the head ofa pile is from three to four minutes.

This complicated machine performed its work with great precision, although severalengineers continued to prefer that used by Label ye for cutting off the heads of the piles atWestminster Bridge: there can be no doubt that De Cessart’s machine, from the varietyof its movements and cost of construction, can only be adopted where very extensive worksare to be executed; the more simple the saw is set, as long as it can be maintained in atruly level position, the better; for scaffolding, if not solidly put together, is very liable toproduce by its change of form very great inequalities in the work performed. A sawmounted on an iron frame, and made to traverse upon two rails of the same material, wouldmost correctly and efficiently’ execute the work, for there could be no difficulty by such an