Gebrüder Fromme
telescopic alidade (topography angle plotter) Gebrüder Fromme
record number: 24
instrument type: telescopic alidade (topography angle plotter)
manufacturer: Gebrüder Fromme
serial number: 1001
weight: 1.82 kg
dimensions (l/w/h): 43/11/20 cm
year of manufacture: 1890
instrument set up: on the plane table (already horizontal)
tubular level and tilting screw
centering above the point
Telescope
diameter of objective: 27 mm
magnification: /
type: Ramsden's retractable eyepiece
cross hairs/reticule: Reichenbach's crosshairs

The plane table with telescopic alidade (kipregel) was made in the 1890s. The instrument was used for graphical measurements. On a piece of paper placed on the plane table, we map the station point. In the position where the telescope is used to aim at a point, the movable part of the ruler is aligned with the station point – the ruler materialises the sighted direction. The Reichenbach distance meter is used for optical reading of the distance on the tacheometer staff. The distance is applied to the drawing surface in the appropriate scale with the bow compass. There are two additional metal plates with vernier graphic scales 1°: 1000 and 1°: 2880.

In 2016, the plane table with telescopic alidade was polished and partially lacquered.