A prism paralleloscope is a piece kit used by

artillery Artillery is a class of heavy military ranged weapons that launch munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during siege ...

units as a

gun A gun is a ranged weapon designed to use a shooting tube (gun barrel) to launch projectiles. The projectiles are typically solid, but can also be pressurized liquid (e.g. in water guns/cannons, spray guns for painting or pressure washing, p ...

aiming point {{Unreferenced, date=April 2007 In field artillery, the accuracy of indirect fire depends on the use of aiming points. In air force terminology the aiming point (or A.P.) refers to holding the intersection of the cross hairs on a bombsight when fixe ...

. It is a type of paralleloscope that uses a prism instead of a plain mirror. Its purpose was to function as an aiming point in the horizontal plane when laying for

indirect fire Indirect fire is aiming and firing a projectile without relying on a direct line of sight between the gun and its target, as in the case of direct fire. Aiming is performed by calculating azimuth and inclination, and may include correcting aim ...

artillery.

Description

The prism paralleloscope entered service with the British Army in the late 1950s. It was permanently fitted in a fibre-glass case with a lid. This case was mounted on two short metal vertical poles so that it was about above the ground, these vertical poles were held together by two horizontal rods slightly shorter than the paralleloscope case. Once mounted the lid of the case provided a 'canopy' above the paralleloscope. Paralleloscopes entered British service in the 1920s-1930s. These early versions were a mirror about long and wide, mounted on a tripod about high and positioned a few yards (or meters) away from and to the side of a gun on its dial sight side. Each gun in a battery had at least one. When a gun was oriented in its centre of arc it recorded the paralleloscope as one of its aiming points (other types of aiming point were a distinctive distant topographical feature or a pair of aiming posts). With a paralleloscope the gun layer set the zero line deflection or bearing of fire on his dial sight and aimed his sight at its reflection in the paralleloscope. As the gun fire and its trail(s) bedded in and the gun moved back, the reflected image of the sight moved along the paralleloscope. It was particularly useful at night because it removed the need for aiming points with lights attached to them. If the gun had a very wide arc of fire then more than one paralleloscope was required for each gun.

References

{{DEFAULTSORT:Prism Paralleloscope Artillery components