Descripción
French manuscript written in brown ink in a French cursive hand, pages ruled in red, 21 lines per page. 15.3 cm x 9.5 cm, (58) pp. Bound in contemporary limp vellum with remains of green silk ties. A presentation copy with the dedicatee¿s name left blank. Clean and fresh, an excellent copy. Very rare manuscript user¿s manual for the famous terrestrial and celestial globes by the van Langren cartographic dynasty, notable as the first to employ the highly accurate star observations of the ¿tresfameux¿ Tycho Brahe ¿ whose contribution is duly acknowledged (fol. 9v). Well into the age of print, these manuals were handwritten rather than printed because the globes which they accompanied were luxury articles and relatively few were produced, notwithstanding their importance. The celestial globes of Van Langren (1594), and later Blaeu, soon rendered Mercator¿s great globes obsolete. As early as 1590, the young Arnold van Langren was sent to Hven to take advantage of what was at the time the most advanced celestial observatory in Europe. ¿When Arnold came to Uraniborg, Tycho¿s plan to publish his stellar positions was already formulated, but the observations and calculations that resulted in the catalogue of 777 stars had not been completed. While Tycho could have provided Arnold van Langren with the newly calculated positions of some stars, perhaps even interim locations for most of them, it seems quite likely that he would have advised the Dutchman to await the completion of this work before beginning a globus Tychonicus. He may even have withheld his consent at this stage.¿ (Adam Mosley, Bearing the Heavens, p. 240). Tycho¿s own Progymnasmata also makes reference to the visit: ¿Jacob Floris, citizen of Amsterdam, a great expert in the making of celestial and terrestrial Globes, having sent here his son, skilled in the construction of the same, decided to prepare a certain celestial globe following this rectification of ours of the places of the Fixed Sars, which in its certainty and skillful elaboration is about to greatly surpass those hitherto employed.¿ The present guide directs the user in the workings of both Langren¿s celestial and terrestrial globes, giving both a general introduction and practical working examples in solving geodetic and astronomical problems. According to van der Krogt, the van Langren manuals are based in part on Robert Hues¿ Tractaet ofte Handlinge van het gebruijck der Hemelscher ende Aertscher globe (1st ed Amsterdam, 1597), and are in part original. ¿Among other things, van Langren makes use of a separate ¿gnomon sphareicon¿ (sphaerical angle bar), a small instrument which makes it possible to place a perpendicular line easily on the spherical globe¿. On f4r Langren discusses the astronomical implcations of the recent calendar reform under Gregory XIII, while on 11r he mentions the influential mentor of Tycho, Landgrave Wilhelm of Hesse-Kassel¿s method of observing stars by their almucantar and azimuth ¿ a procedure which would later become adopted as the standard method for determining stellar positions. Langren also here explains his decision to include the 32 winds by which modern navigators divide up the sky, which are apparently noted on the globe in Flemish. Despite other similar references to the recent advances of Pedro Nunes (23v), and Tycho Brahe, the present manuscript is above all a practical rather than theoretical guide to the use of the globes in understanding celestial and terrestrial mechanics. Imperative instructions - ¿tournez vostre Globe ainsi¿¿ ¿Cherchez sur le Globe le degre du Soleil¿¿ ¿ evidently enabled the user to manipulate his globes with or without an instructor present. . N° de ref. del artículo 5134
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