Independent line of sight

The independent line of sight meant that two gunlayers were used, one on the right side controlling elevation, one on left controlling the range. This speeded up gunlaying, especially with direct fire against at moving targets, and increased the rate of fire. It was first brought out by the French in their 75mm Mle 1897 field gun, and was later adopted also by the British army. Although both Krupp and Rheinmetall had introduced carriages with sight of this type, the German army did not appreciate them.

The difficulty of fitting reciprocating sights to carriages of this type was an objection against its introduction. Moreover Germans military experts emphasized that the advantage of the independent line of sight was scarce, thinking that the question of rapid fire in the field artillery had less to do with slow laying operations than with preparating ammunition.

Usually the armies which bought French guns choose the independent line of sight, while who adopted German guns, preferred the ordinary way of sighting, where all laying operation were performed by one man, the gun layer. The main exception was Bulgaria, that required that its Schneider field guns had not independent sighting apparatus: the sight and aiming circle being attached to the cradle, both moved in elevation with the gun.

The quadrant elevation of the piece consisted of two parts:

- the elevation necessary to reach the target if it were on the same level as the gun.

- the correction to this elevation required by the difference of level of the gun and target (angle of site).

With the independent line of sight the two parts of the quadrant elevation were applied to the gun independently. An intermediate rocker and two elevating systems, A and B, were provided as shown in the picture. The sight was fixed to the rocker, and for direct fire the gunlayer handled the lower elevation system (A), which moved the rocker as well as the gun in elevation. In this way the angle of site was automatically corrected, when the line of sight was brought upon the target.

The other elevating mechanism (B) was between the rocker and the gun and was handled by another gunner who elevated the gun until the proper range appeared on a range scale. The change in range did not affect the setting of the lower elevating mechanism, and the gunlayer was thus free to devote his whole time to keeping his line of sight upon the target, without being compelled to take his eye from the telescope. The above method has the objection, however, that it is difficult to make the necessary correction in the range drum for difference in level of trunnion axis.

Artillery equipments at the beginning of World War I
Country	Maker	Calibre	Adoption year
Field guns fitted with independent line of sigh
Argentina	Krupp	75mm	1908
Chile	Krupp	75mm	1910
China	Skoda	75mm	1912
Great Britain	Vickers	76.2mm	1903
Great Britain	Vickers	83.8mm	1903
France	Puteaux	75mm	1897
France	Schneider	75mm	1912
Greece	Schneider	75mm	1906
Italy	Krupp	75mm	1906
Italy	Krupp	75mm	1911
Italy	Deport	75mm	1911
Mexico	St. Chamond	75mm	1902
Portugal	Schneider	75mm	1904
Russia	Schneider	76.2mm	1913
Serbia	Schneider	75mm	1907
Spain	Schneider	75mm	1906
Sweden	Krupp	75mm	1902
Field guns not fitted with independent line of sight
Austria-Hungary	Skoda	76.5mm	1905
Belgium	Krupp – Cockerill	75mm	1905
Brazil	Krupp	75mm	1905
Bulgaria	Schneider	75mm	1904
Denmark	Krupp	75mm	1902
Germany	Krupp – Rheinmetall	77mm	1896/1906
Holland	Krupp	75mm	1903
Japan	Krupp – Arsenal Osaka	75mm	1905
Norway	Rheinmetall	75mm	1901
Romania	Krupp	75mm	1903
Russia	Putilov	76.2mm	1900
Russia	Putilov	76.2mm	1902
Switzerland	Krupp	75mm	1903
Turkey	Krupp	75mm	1903