The granite and hard stones were also sawn, and cut with tubular drills. The saws were blades of copper, which carried the hard cutting points. The cutting material was sand for working the softer stones, and emery for harder rocks. As far back as prehistoric times, blocks of emery were used for grinding beads, and even a plummet and a vase were cut out of emery rock (now in University College). There can be no doubt, therefore, of emery being known and used. The difficult question is whether the cutting material was used as loose powder, or was set in the metal tool as separate teeth. An actual example was found at the prehistoric Greek palace of Tiryns. The hard limestone there has been sawn, and I found a broken bit of the saw left in a cut. The copper blade had rusted away to green carbonate; and with it were some little blocks of emery about a sixteenth of an inch long, rectangular, and quite capable of being set, but far too large to act as a loose powder with a plain blade. On the Egyptian examples there are long grooves in the faces of the cuts of both saws and drills; and grooves may be made by working a loose powder. But, further, the groove certainly seems to run spirally round a core, which would show that it was cut by a single point; and where quartz and softer felspar are cut through the groove floor runs on one level, and as the felspar is worn down by general rubbing, the quartz is actually cut through to a greater depth than the softer felspar. This shows that a fixed cutting point ploughed the groove, and not a loose powder. Also, the hieroglyphs on diorite bowls are ploughed out with a single cut of a fixed point, only one hundred and fiftieth of an inch wide, so it is certain that fixed cutting points were used for hand-graving. There is no doubt that sawing and grinding with loose powder was the general method, but the use of fixed stones seems clearly shown by the instances above. The large hieroglyphs on hard stones were cut by copper blades fed with emery, and sawn along the outline by hand; the block between the cuts was broken out, and the floor of the sign was hammer-dressed, and finally ground down with emery. Hammer-dressing was largely used in all ages on the hard stones; the blows crushed the stone to powder, and the stunning of the surface was often not quite removed by grinding, and shows as white spots. The hammer was usually of black hornstone, a tough amorphous quartz rock.