Dip sector

The dip sector ( Greek - Latin ) is an angle measuring device that works with the help of two plane mirrors . It could also be used to measure the distance from the horizon and from coasts.

The dip sector was first constructed in 1817 by Wollaston (1766–1828) and is based on the same principle as the mirror sextant invented by Isaac Newton (or Robert Hooke ) and like the reflection circle . Even John Hadley (1682-1744) had made a similar instrument.