We have a sextant which I used to use every week for practice.
Measure the altitude of Polaris above the northern horizon, using the sextant.
It is only after several minutes of sextant observation that the navigator decides that he has witnessed the passing of maximum altitude (i.e.
Zacli published Tables of the Sun (Gotha, 1792; new and improved edition, ibid., 1804), and numerous papers on geographical subjects, particularly on the geographical positions of many towns and places, which he determined on his travels with a sextant.
In the case to the side are many instruments including the first sextant, made by John Bird in about 1757.