bavarikon4UDescription
Instruments with a quarter, sixth or eighth measuring circle are often sufficient to measure the angles between landmarks, church steeples and celestial objects. They are called quadrants, sextants or octants. To determine larger angles, intermediate marks are used and the measured partial angles are added together.
From Hadley's mirror instrument, which is used to measure elevation angles above the sea horizon (1731), the development in Germany went on the one hand towards Brander's measurement of angles on land with an artificial horizon (1764), and on the other hand to angle measurement without any horizon between any objects. As with Hadley, the particular advantage here was the independence from a fixed location: measurements at sea and on horseback became possible. All three methods used the principle of angle doubling by mounting the mirror on the instrument's movable leg. Brander and Höschel also used the more precise division of a linear scale, instead of the usual angular scale, to achieve the highest possible accuracy with a pocket instrument.
The mirror sextants manufactured by Brander use the principle of momentary measurement and more careful reading of the measured value at rest later (measured value storage), a principle that is advantageous for many civil surveying, astronomical and military applications. (Source: Brachner 1983)