"Autograph Note From Joseph Jérôme De Lalande"Autograph note (n.p.n.d.) entitled "Way of tracing a meridian by the passage of the polar star to the meridian". 1p 1/3. In-12 °. With drawing explaining the purpose of the manual.
Way of tracing a meridian by the passage of the polar star to the meridian, given to M. de Charleval.
Suspended from 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 plumb, which must serve as a stile in the room, where the 'we want to draw a meridian; arranged lad. string which carries the lead, so that it hides At the same time, the polar star A; The Root of the big tail of the big bear B; And the join of La Cassiopée C; then in and assured that lad [ite]. Polar star A, is certainly in the meridian plane: observing that Lad [ite]. Polar star A, is always on the side of La Cassiopée. So that when Lad [ite]. Cassiopeia and almost on the head, Lad [ite]. Polar star A. and above the pole, there as we can see in the figure Cy next to it. And that when Lad [ite]. Cassiopeia and the side of the northern horizon, then lad [ite]. Pole star A, and below the Pole & c.
Some observations of the Passage through the meridian from October 20 to November 5. The polar star passes to the meridian above the pole between 10. And ii. Evening hours.
From 5. Nov. Until 20 dud [it] The polar star passes to the meridian above the pole, between 9 am and 10 am. evening.
From led [it] .20. nov. Until December 5 passes between 8. and 9. o'clock in the evening.
From Dec 5. Until 18. dud [it] passes Between 7. and 8. er. evening.
From December 18. Until 31. said pass Between 6. and 7. er. evening. And so Lad. Star passes to the meridian under the pole - Between 6. and 7. o'clock in the morning, time at which it can also be easily observed in the same day & c.
Under the drawing: see the treatise on gnomonic in4 ° by deparcieux. 1741. Pag. 89. Plate 17. Figure 133.
Where this is related. In gnomonic a meridian is an instrument or a construction allowing to locate the precise moment of solar noon, it is in a way a sundial.