Onderwys in 't Regte Gebruyk van het Hemels-Plyn strekkende tot nut en vermaak der liefhebbers

Published by Jochem Hasebroek, Amsterdam, [c. 1722]

Large engraved celestial chart with a rotating printed paper ring (volvelle or rete) on an off-centre axis to indicate the part of the sky visible at any date and time and to make a variety of celestial calculations, all for the Netherlands’ latitude of 52 degrees. With letterpress instructions by Calman on a separate printed slip at the right. The sky image 32.5 cm in diameter; the whole chart with the letterpress slip as mounted 56 x 66.5 cm. A string serves as a pointer for aligning the scales in the stationary and rotating parts. Coloured by a contemporary hand.

The chart is here in its third state, but we have located no complete example of any earlier version. The Boerhaave Museum in Leiden has the chart without volvelle or instructional text, published by Doncker, but the 1664 edition described in Doncker’s advertisement clearly included the volvelle and instructional text. Perhaps the surviving chart is the 1684 version mentioned but not seen by Bierens de Haan, who provides neither a detailed description nor a source for his information. They and the present version (printed from Doncker’s plate c. 1722) seem to have appeared only as separate publications, hence their great rarity.

The circular border around the sky image and the outer part of the volvelle include scales with several kinds of data so that the chart can be used for various purposes. one can use the string to align the time in the volvelle with the date in the border of the chart, so that the part of the sky visible at that moment appears inside the volvelle. The chart with its volvelle, scales and string can also be used to calculate times for the rising and setting of constellations at various dates (or to calculate the present time based on the position of the stars). Fifty-three constellations are numbered quarter by quarter (15, 9, 14 and 15), with a Dutch key identifying them in each corner. Calman’s instructional text, printed letterpress on a separate slip (495 by 185 cm) and mounted to the right of the chart itself, describes the different scales, etc.then presents nine “proposals” (giving examples of the use of the chart).

In the plate of the star chart itself is engraved, “Auct. J. Stampioen. ‘t Amsterdam by Iochem Hasebroek” but Hasebroek’s name is larger and in a different style than the rest of the lettering, and one can see traces of an earlier name under it. Although the older name cannot be deciphered, one can see that “Hendrick Doncker” would fit (with traces of the h and Do, and marks where the ascenders to the d, k and k would have been), making it clear that the present chart is printed from Doncker’s original plate. Calman advertised his Amsterdam boarding school for calligraphy, mathematics, etc. in 1722, and Hasebroek (1682- 1756) is recorded as a sea chart publisher and instrument maker from 1714 to 1743. Koeman IV, p. 5 (no location noted; cf. p. 153); Warner, Sky Explored, p. 260, no. 1c (no location noted; cf. p. 247); Alder Planetarium on-line database A-259; cf. Bierens de Haan 4516 (1684 ed., not seen: see his Bouwstoffen II, pp. 386 & 429 note 5); E.O. van Keulen et al., “In de Gekroonde Lootsman,” item 4 & illustration between pp. 64 & 65 (1680/1696 Vooght/Van Keulen ed.); not in BMC Printed Maps; Zinner, Astron. Instrumente; NCC/Picarta; OCLC WorldCat