'T Derde deel van 't Licht der zee-vaert, inhoudende de beschryvinghe der zeecusten van de Middelandtsche...

staff, and may be slid back and forth along it. And so that it goes smoothly and securely upon it, make a steel or copper spring in the bottom base of that hole, which drags from underneath against that staff and forces it firmly, as O P. Lastly, make a small cross-piece cruysken small cross-piece like Q with a hole therewith that one may place it on the long cross M N, and set it firmly with a small screw from behind, as high or low as the usage requires. At the forward end, make a flat ear one or one-and-a-half inches wide like R S, not straight

A technical illustration of a surveying/navigational cross-staff labeled "N.o 2". It shows a long horizontal stock with numerical scales, a vertical sliding assembly, and alternate positioning lines M, N and O, P.

Om now to mark this staff for use, do as follows:

nor flat, but slanted or tilted, such that when all these parts are joined together properly, the plane of that ear and the slanted plane of the slider H always stand parallel to each other. That is, they always make equal angles, or together stand just as much out of the square against the staff A B. These parts being thus prepared and put together, the form of such an instrument is like the following figure marked N.o 2.

Make a smooth board about as wide as the long cross is long, and as long as the staff A B,