Artillery Instruments

One of the most basic instruments used in artillery is that for determining the elevation angle of a gun. It was known from the earliest experiments with guns that a given angle of elevation together with a fixed amount of propelling charge would achieve (theoretically!) the same trajectory every time the gun was fired. Variations in the quality of the propellant, the weight of the projectile, the condition of the bore, the weather conditions etc. all affected this trajectory, but for their purposes, gunners were able largely to rely on this angle of elevation to achieve a known range.

It was therefore important to be able to set this angle on the gun. Their solution was the gunner's quadrant. This simple device had an arm that went into the barrel, a quarter circle (quadrant) measuring instrument and a plumb bob. As the gun elevated, so the plumb bob's string moved on the quadrant, allowing the gunner to read the angle.

Over time, of course, this device became gradually more sophisticated, acquiring a levelling bubble to replace the plumb bob and achieving very high accuracy by the means of precision engineering. However, in essence, that is all that a gunner's quadrant is - a means of measuring the angle of elevation of a gun's barrel.