Beschreibung:

A 17th-Century English wooden triangular quadrant, or jointed rule, unsigned , but possibly by John Browne in boxwood and brass ( cross piece, plumb line and sights missing ) -- 18¾in. (47.8cm.) long Scales on the sector side The line of lines and line of sines, sharing a common middle line; lines of secants; lines of tangents; sines and versed sines (ie co-sines); lines of chords and equal parts. Scales on the quadrantal side On the lower edge a protractor scale of 180°, the divisions being radial from a point at the end of the line of general sines on the upper arm where the angle between the two arms is 45°; a perpetual calendar, table of twelve stars for finding the time at night, and a Zodiac/calendar scale (see below); a line for finding the hour and azimuth in a particular latitude; a line of natural versed sines which has a corresponding line on the lower edge of the upper arm. Above this is a line of lines, a line of general sines for jour and azimuth at one particular latitude (51° 30') and on the outer edge is a line of 24 hours, 360° and the twelve Zodiacal signs for finding the hour by Moon and fixed stars. At the end of the arm are tables of weekdays, leap years and epacts (see below). Three mnemonic tables 1) Calendar We Da S M T W T F S Do Le d c b a g f e Le Ye (16)68 80 64 76 60 72 84 Epa 6 9 12 25 28 11 23 2) Perpetual Calendar Mon 1/9 6 3/11 8 5/2 7/10 4/12 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Daic 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 0 0 0 0 3) Stars - selection of twelve stars 1 Pleiades 03.24 23.10 Tau 2 Bulls eye 04.46 15.48 Tau 3 Orio:gird 05.18 01.19 Ori 4 Lil:Dogg 07.20 06.08 CMi 5 Lyons hart 09.50 13.50 Leo 6 Lyons tayl 11.30 16.30 Leo 7 Arcturus 14.00 21.04 Boo 8 Vult:heart 19.33 08.00 Aqu 9 Dolp:head 20.30 14.52 Del beta? 10 Pega:mouth 21.27 08.19 Peg 11 Fomahant 22.39 31.17 PsA 12 Pega:lo:wing 23.55 13.19 Peg