ChiCom North Vietnamese Army Rocket & Artillery Clinometer 1969 with Manual

This is an uncommon ChiCom made indirect fire inclinometer aka clinometer.

It comes in the issue wooden box and is a necessary part of any rocket launching or artillery crew served equipment.

A clinometer is used to accurately set the elevation of a rocket, mortar, artillery or heavy machine gun so that the shells follow the correct trajectory and land at the range required.

In order to use the inclinometer, the base was placed on the barrel and the central arm moved up and down until the spirit level built into it was showing level, at this point the scale could be read to see the angle of the barrel. The spirit level itself works.

The clinometer could be also be hastily rested on a field gun by a gunner to quickly read off the angle of elevation, before adjustments were made.

Still in Cosmoline.

The data plate characters 炮用象限仪 translate to artillery quadrant.  It also has Russian Cyrillic on it ГОСТ  3299-46. This means GOST [State (Quality Control) Standard] 3299 established in 1946.

The Accompanying Chinese language booklet is dated 1969, is 10 pages long and shows the quadrant.