Handleiding tot de kennis en het gebruik der hemel- en aard-globen.
- Author: COVENS, Cornelius
- Publication place: Amsterdam
- Publisher: Mortier, Covens and son
- Publication date: 1802.
- Physical description: Octavo. 8 printed tables and 14 folding engraved plates; contemporary half calf, speckled paper boards, gilt.
- Dimensions: 227 by 137mm. (9 by 5.5 inches).
- Inventory reference: 17686
First and only edition of this manual for the construction and use of an innovative type of terrestrial globe by Cornelis Covens (1764-1825), a member of the well-known Amsterdam Covens family of publishers, mapmakers and cartographers.
In 1802 the Amsterdam mapmaker Cornelis Covens (1764-1825) had published a 12-inch terrestrial globe with a new construction. By means of a complex mounting with numerous brass rings, Covens designed this Copernican globe – inspired by one brought out by the English instrument maker George Adams senior (1704-1772) – to show the real movement of the earth and other related phenomena. Initially Covens didn’t intend to make a new construction for his celestial globe, because in his opinion the common celestial globe sufficiently shows the apparent movement of the sky. The Leiden professor Jacob de Gelder (1765-1848), however, didn’t agree with him. According to De Gelder, the ideal celestial globe was one that could be adjusted to an arbitrary “epoch”. He therefore advised Covens to make a “new” celestial globe as well. Shortly afterwards Covens indeed designed a a new globe, which served as the counterpart of his new terrestrial globe. Covens’s new globes got an enthusiastic scholarly reception. Because the mounting included many brass rings, however, the globes were very expensive compared to common globes. Consequently, Covens’s “unusual” globes proved a commercial disaster.
Each of the folding plates is illustrated with several schematic figures of terrestrial and celestial globes, astronomical diagrams, planetary motion, and directions on mounting the globes.
- XXIV, 415, 20,  pp. Elly Dekker & Marco van Egmond, "Het 'ongewone' globepaar van Cornelis Covens …", in: Caert-Tresoor, 22/1 (2003), pp. 1-13, with illustr. of the "unusual" globes by Covens in the Koninklijk Huisarchief.