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John Senex

Zodiacus Stellatus Fixas Omnes Hactenus Cognitas, Ad Quas Lunae Appulsus Ullibi Terrarum Telescopio Observari Poterunt, Complexus, London 1718

Zodiacus Stellatus Fixas Omnes Hactenus Cognitas, Ad Quas Lunae Appulsus Ullibi Terrarum Telescopio Observari Poterunt, Complexus.

La tavola, una delle rare copie colorate a mano esistenti, viene pubblicata per cortesia di

che attualmente la propone in vendita dal suo sito descrivendola con la presentazione seguente:

First edition of this 3 sheet chart of the Zodiac, published by John Senex in London .

John Senex was one of the first English publishers to produce celestial charts. As noted by Kanas,

In part through his collaboration with Halley, Senex produced a number of celestial maps . . . which were quite popular with astronomers and navigators. . . One of these maps was originally published in 1718 and showed the zodiac constellations in three long strips arranged vertically over two pages on a map labeled Zodiacus Stellatus Fixas Omnes Hactenus Cognitas . . . Each srip was centered 8 degrees above and below the ecliptic using a cylindrical projection with geocentric orientation. . . Since the stars were derived from Halley's unauthorized edition of Flamsteed's catalog, [Flamsteed having refused to publish his work during his lifetime] . . . , the appearance of this and other maps by Senex created great consternation at Greenwich [where Flamsteed was the Royal Astronomer].

Senex's work would remain the only representation of the constellations of the Zodiac until Pierre Charles Le Monnier's work of 1755.

The map includes a fantastic description legend at the bottom, which begins as follows:

The DESCRIPTION and USE of the Starry ZODIAK. Finding that nothing would more conduce toencourage Persons to ye Study of Astronomy than to remove those difficulties which commonly deterr BEginners; and haveing by ye favour of a Person of Quality, procured a Copy of the Britannick Catalogue of Fixt Stars, I was persuaded ye I shold do the Science a considerable piece of service, if I represented to a competent scale and in their true Sitauation and Magnitude, all those Starrs to whic the Moon or Planetts can at any time make their Appulses. For by this means those that are provided with a Telescope only may be able to Judge of ye accuracy of our Astronomical Tables & Ephemerides; and by ye farther help of yes Micrometer & Pendulum Clock, may make such Observations as may be of use to compleat ye Theory of ye Celestial Motions; ye opportunitys of Observing being readily had by ye help of ye Zodiack.

The British Catalogue ye being adopted to ye beginning of ye year 1600, I was advised to follow it without reducing it to ye present Time; because it would always be necessary to allow for ye increase of ye Starrs Longitude in succeding Years, and it is no more work to subtract 30 or 40 then 15 or 20; This reduction being easily made, by subtracting 15 min: for every 18 years lapsed since 1690, from ye place of ye Moon or Planet found in te Ephemerides, when you would compare them with ye Starrs places in the Zodiack.

That ye Planets might be transferrd with more certainty into it I have drawn ye lines drawing each Degree both of Longitude and Latitude into quarters sufficiently distinguished from ye entire Degrees by ye smallness of ye stroaks for which reason there will be no need to use Compasses. Our Scale being so large as to afford a 10th of an Inch to each quarter of a Degree. Thus for Example if you desire to see how ye 3 Superiour Planets are situated among ye fixt Starrs ye 12st of April 1718; We find by ye Ephemerides of Mr. G. Parker for which are computed from Astronomia Carolina with sufficient care ye Saturn . . .

La tavola, di formato 127,5x53,8 cm, pubblicata a Londra nel 1718, riporta, in proiezione cilindrica e in visione geocentrica, le stelle suddivise in sei classi di magnitudine poste a nord ed a sud dell'eclittica per una escursione di 8° di latitudine. La posizione delle stelle, identificate con il metodo introdotto da Bayer con lettere dell'alfabeto greco, è calcolata per il 1690. Essendo la proiezione cilindrica la scala della carta è di mezzo pollice ogni 15' di arco. Le costellazioni riportate, essendo quelle dello zodiaco, sono soltanto quelle tolemaiche e sono disegnate, su due fogli, in tre fasce. Ogni segno zodiacale vi viene presentato in un rettangolo che misura 12 pollici in larghezza per 6,25 in altezza. Sono sovrapposti due reticoli di riferimento, quello equatoriale con linee ogni 1° di declinazione ed ascensione retta, quello eclittico con linee ogni 15' di longitudine e latitudine.

Anche questa tavola, come tutte le altre di produzione di J. Senex ,hanno come riferimento il catalogo stellare pubblicato da Halley nel 1712 che riportava oltre a propri dati anche quelli ricavati dalle osservazioni dell'astronomo reale Flamsteed che li aveva concessi per l'uso ma non per la pubblicazione.

Stellarum Fixarum Hemisphaerium Boreale, the Northern Hemisphere Projected on the Plane of the AEquator in which all the Stars contain'd in the Britannick Catalogue (as Publish'd by Dr. Halley) are carefully laid down and adapted to the beginning of the year 1690. The Asterismes being drawn to answer the description of the Ancients. London 1721-1728

Stellarum Fixarum Hemisphaerium Australe, The Southern Hemisphere Projected on the Plane of the AEquator in which all the Stars in the Britannick Catalogue and those Observ'd by Dr. Edm. Halley at the Isl. of St. Helena, are carefully layd down for the Year 1690 by Joseph Harris. London 1721-1728