Schneider field howitzer sight
The Schneider field howitzers were equipped with a drum sight on which could be assembled a panorama telescope, like in the Bulgarian howitzers, or simply a collimateur. It was composed by a bracket articulated on the right trunnion of the carriage and was equipped with a level I to correct the slope of the trunnions and keep vertical the rotating axis of the panorama telescope. This bracket had a frame supporting the sighted apparatus and the spirit level. The frame carrying the sighting apparatus pivoted, so that the optical axis and the spirit level, compared with a horizontal reference plane, could take an angle equal to the quadrant angle. In this way, the howitzer could be pointed both in elevation and in direction, simply pointing the optical axis at the target or at the aiming point, and bringing the spirit level between its marks, after having given the sight angle. The initial condition was that the optical axis of the sighting apparatus was put horizontally at zero in parallel to the barrel axis placed horizontally too, with the platform of the carriage placed horizontally as well, the sight angle at zero and the bubble of the level between their marks.
The frame turned by means of the worm H, which controlled also the range drum D. The angle corresponding to a certain range was given changing the drum graduation in relation with the pointer K. The drum had five concentric circles containing the graduation proportional to the muzzle velocity of the different battering charges of the howitzer. The graduations were seen in the window of the fixed display F that covered the drum. The display M, adjustable by hands, had some windows, each corresponding with a given muzzle velocity. Only one of them could be bring in front of the window of the display F, in order to read the graduation that should be adopted with the chosen velocity.
By means of the milled head A the level I was adjusted to correct the slope of the trunnions; after having loosened the nut B, the display M was moved in front of the display F by means of the lever C, then the nut B was bounded again. The angle of sight was given by means of the head R, the quadrant angle by means of the milled head H, the deflection was put by means of the goniometer lever G, the plateau P showing the millièmes and the drum T the hundreds of millièmes. The spirit level was brought between its marks by means of the lever of the elevation gear and the vertical line of the reticle of the panorama sight (or the cross of the collimateur) was pointed at the target or at the aiming point by means of the operating handle of the traversing gear.
PELOUX H. : “Matériels de campagne et de siège Schneider et Cie”. Revue d’artillerie : LXXIX (Octobre 1911 – Mars 1912), pp. 392-394.