new and improved forms of the tool. See Fig. 3214, page 1473. See also pipe-wrench, Figs. 3735-3738, page 1711. Figs. 7366-7368 show several forms of wrenches, for various purposes and adapted to different situations. In the self-adjusting wrenches and pipe-tongs (Fig. 7369), the curved inner faces of the jaws are serrated; various sizes of pipes may be firmly grasped by opening the jaws to a greater or less extent and inserting the pipe to a proper distance