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

just as far from that same plane, make a small notch in that aforementioned peg L. Thereafter, fasten a small string or some other smooth cord with each end in those two small holes of that aforementioned bar, as at I and K, and with the middle in the notch of this aforementioned peg at V, such that such a string being pulled tight stands everywhere equally far separated from the plane B C F G. From the point L, also make a semi-circle slightly raised from the plane, as M D N, such that the line M N is parallel with the top edge of the box, or the bar, and the line L O (dividing that semi-circle into two quadrants) is at a right angle to I K. Divide that semi-circle on the inside into two times 90 degrees. Finally, make a handle of copper or wood, as P Q R, by which the box hangs such that the top plane A B C D hangs exactly level, and the south side B C F G, as well as the edges B F, C G, and the line L O, hang exactly plumb. This being thus equipped, the use of it is as follows:

Three or four hours before noon, more or less, turn the edge C G exactly towards the sun, so that the shadow of one side of the string L K falls exactly on or along the line K I, and observe which degree of the compass then comes to stand next to the copper edge H, which I assume to be the 30th degree from the north towards the west, as in the figure following here at A. At the same moment, one also observes the altitude of the sun by the shadow of the peg L in the semi-circle M O N (or one takes it more sharply and surely with a protractor or astrolabe), which we here assume to be 25 degrees. One marks all this down for remembrance. Furthermore, wait until after noon until the sun has again descended to the same altitude as before of 25 degrees, and then turn the edge B F exactly towards the sun, so that the shadow of the side of the string L I falls again exactly along the line I K, and observe what degree of the

A circular diagram represents a compass. The outer rim is a protractor scale graduated in degrees from 0 to 90 in each quadrant. Letters A, G, F, C, E, B, and D are marked along the upper arc. At the center is a sixteen-point compass rose. The north point is indicated by a fleur-de-lis aligned with the letter C. The center of the rose contains a floral emblem.

compass then comes to stand next to the copper edge H, which I assume to be the 30th degree from the north towards the east, as at B. This being so, the middle of the arc A B, which is C, is the true desired north point; and because the lily points right at it, such a compass has no deviation, but points exactly north. If in the aforementioned observation of the afternoon...