Master Hood's Cross-staff: a reconstruction

摘要

The end of the 16th century was the start of a new era in the development of navigational instruments. By this time one of the principal instruments for celestial navigation at sea was the cross-staff. The others were the mariner's astrolabe (Fig. 1) and the quadrant (Fig. 2). The cross-staff is a wooden instrument consisting of a square staff and up to four sliding transoms or vanes (Fig. 3).2 For each vane a scale was engraved on one of the sides of the staff.