slide rule versions of Gunter's scale, both 18th century, boxwood with brass ends, one English, one Dutch (or Dutch owner), both display navigation scales for leagues, rhumbs, sines, tangents, meridian line, equal parts and sines of rhumbs in addition to the logarithmic number scales, both unsigned, but one with owner's name 'P Holm Schip Reght door see' stamped to side (this rule is warped but slide still operates smoothly), longest 31.2cm.