Description

This rare brass slide rule was made in 1904 to be used with the Cannon de 155 CTR. Dated 1904, only 122 such cannons were made, with 104 of them available in 1914 (see link below).

The slide rule measures 12 inches long and is 1/2 inch thick. It has various descriptive scales engraved to both sides including:

Tir fusent plongeant (Burst of Plunging Fire).

Distances de debouchage. (Clearing distances).

Vingtiemes de hausse (Twentieths of increase).

Reglette de correspondance pour le tir plongeant fusant (Matching strip for plunging armour-piercing shell).

The centre sliding scale is of steel, moveable by depressing the button to the side.

These slide rules are more rare then the cannons they were made for, one of which is in the Royal Army Museum, Brussels, Belgium. (see link below).

passioncompassion1418.com/Canons/Eng_AfficheCanonGET.php?IdCanonAffiche=172