LALANDE Joseph Jérôme Lefrançois de (1732-1807). Autograph note (s.L.N.D.) entit…
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LALANDE Joseph Jérôme Lefrançois de (1732-1807).

Autograph note (s.l.n.d.) entitled "Maniere de tracer une méridienne par le passage de l'etoile polaire au méridien". 1 p 1/3. in-12. With drawing explaining the purpose of the notice. "Maniere de tracer une méridienne par le passage de l'Etoile polaire au méridien, donnée à M. de Charleval. Suspended in the field a string with a lead, as far as possible from the window frame of a house, or from a corner of the wall which is well in line with the lead, which must serve as a symbol in the room where one wants to draw a meridian; arranged the string which carries the lead, in a way that it is not in the way of the meridian. string which carries the lead, so that it hides At the same time, the polar star A; The Root of the big tails of the big bear B; And the joint of the Cassiopeia C; then in and assured that lad[ite]. Polar star A, is certainly in the plane of the meridian: observing that Lad[ite]. Polar Star A, is always on the Side of the Cassiopeia. So that when Lad[ite]. Cassiopeia and almost on the head, Lad[ite]. Polar Star A. and above the pole, the so that one can see in the figure Cy next to it. And that when Lad[ite]. Cassiopeia and on the side of the northern horizon, then the said. Polar Star A, and below the Pole &c. Some observations of the Passage by the meridian from the 20th of October to the 5th of Nov. Nov. The polar star passes the meridian above the pole between 10. and ii. Evening hours. From the 5th. Nov. until 20 dud[it] The polar star passes the meridian above the pole, between 9. and 10. evening. From the 20th of Nov. to the 5th of Dec. passes between 8. And 9. o'clock in the evening. Since Dec. 5. Until 18. ofd[it] passes Between 7. and 8. evening. Since Dec. 18. Until 31. of the said passes Between 6. And 7. evening. And then Lad. Star passes at meridian under the pole - Between 6. And 7. hours of the morning, time to which one can observe it also in the same day easily &c." Under the drawing: "see the treaty of gnomonic in4° by deparcieux. 1741. Pag. 89. Plate 17. Figure 133. Where this is related." In gnomonics a meridian is an instrument or a construction allowing to locate the precise moment of the solar noon, it is in a way a sundial.

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LALANDE Joseph Jérôme Lefrançois de (1732-1807).

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