A large stereo tube of the "coastal sample" of the K.P. Hertz company in Riga, 1914.

This stereo tube, mod. 1912, was intended for the artillery of the coastal fortresses of RIA. The stereo tube was used to study the terrain, search for targets, determine vertical and horizontal angles, and adjust artillery firing. The magnification of the tube is 10X, the lens diameter is 50 mm. It was equipped with a holder, a limb for measuring horizontal angles, a wooden tripod, two greenish-yellow light filters, as well as a special satchel for storage and carrying. In the right eyepiece of this stereo tube, a diaphragm angle-measuring grid with a wire crosshair is installed, which is typical for stereo tubes manufactured by KP Hertz. There is a special lever on the eyepiece to rotate the grid to the desired position for observation. In accordance with the circular of the Main Artillery Directorate No. 61-1912, large stereo tubes were introduced into the fortress artillery instead of large and medium-strength telescopes of the company "K.Votkey", adopted for fortress artillery back in 1893. The divisions of the limb of the BST intended for fortress artillery were in fractions of degrees. and not in the "thousandths", as with field artillery devices. This is the main distinguishing feature of these stereo tubes and is due to the fact that all other artillery fire control devices of the fortress artillery and the sights of the fortress guns had scales in the degree measurement system. On the right decorative ring under the objective prism (on the eyepiece side) there is a S.A. stamp in a rectangular frame, which indicates the use of the device later in the Finnish army. There, apparently, the pipe was repainted from black to gray.