FIRST PROBLEM.

To advise how the instrument should be set up.

A woodcut depicts a decorative drop cap letter I featuring floral and foliate motifs.In a place uncovered on all sides and exposed to the rays of the stars, place a certain stone whose surface, being very flat, is equidistant to the horizon of your region, which will be easily accomplished by the work of a stonemason. On that surface, draw a Meridian line which should pass through the middle of the stone now fixed, as far as can be done. Then, raise the Equinoctial board according to the magnitude of the angle which the equinoctial and the horizon of your region contain, that is, according to the meridian altitude of the equinoctial points, which indeed constitutes the elevation of the pole of the circle. That will be conveniently accomplished if you place two monthly tablets between the horizon and the equinoctial board, whose inclined sides, if produced, meet at such an angle. We have made such ones for the latitude of 47 and a half degrees, which the city of Esztergom almost occupies. We have not, however, added those tablets to the parts of the instrument named above, because other regions with different latitudes require other tablets of this kind. Therefore, with the equinoctial board raised and firmly positioned, place the whole instrument upon the stone disposed in the aforementioned manner, so that the Meridian line of the instrument, which we have drawn on the horizontal board, is most correctly adapted to that Meridian line which is on the surface of the stone.

SECOND PROBLEM.

To know the true place of the Sun by a given day of the month.

The extremity of the ruler of longitude placed upon the proposed day of the month on the annual circle will show the place of the Sun almost in the ecliptic sign-bearer, just as in the common astrolabe.