Cramp Irons

Short pieces of iron, polished on their face, fastened to the under side of the plank, to run the carriage in and out upon the long ribs. They are frequently called the Short Ribs. The two at each end are turned again at the outer ends to guide the carriage, and prevent any lateral motion, and are called Guide Cramps. I have seen them made of bell metal, as having less friction than iron running upon iron.