The technology of drilling hard substances such as stone was investigated, with the objectives of deducing from tool marks on ancient artifacts the nature of the tools that were used to drill the artifacts and of reproducing these tool marks experimentally. Experimental drillings in slate and quartz with drills of, e.g., wood with an abrasive were replicated in silicone resin and examined in the scanning electron microscope. Drilled holes in twenty-eight ancient seals were examined in the same way, and evidence obtained as to some of the drill tips used. Proof was obtained that a wooden drill tip and abrasive were used on certain steatite seals ca 3000 B. C. Initial evidence was found for the adaptation of the bow-drill to form a horizontal spindle for use with a cutting disc; this occurred on seals dated much earlier than had previously been conjectured for this adaptation. Various other tool marks are also discussed. -- AATA