1. This rule was made, or sold, by a French company.  The only reference I can find to the company, from an internet search, is a set of drawing instruments in ivory which was were sold by Dick Rose, who also sells slide rules.

2. The address of the company, 17 rue Béranger, Paris, is still occupied, apparently by several companies, none of which appear to have any connection with technical instruments.

3. The rule appears at first to be a standard Manheim configuration except that the tangent scale, on the reverse, is inverted relative to the sine and log scale.

4. From the general style, the wood and celluloid construction and yellowing of the cursor I would have dated the rule to sometime pre-war. There is however a stamp on the back with the number 166. This could perhaps be January 1966 or simply some indication of the batch.

5. The slide and stock both carry the number 94 stamped on the end. This would appear to be for ensuring the slide and stocks from the same batch were used. In this case the number 166 as a batch number would appear to be superfluous.

6. The rule also has two fine slots cut at both ends of the stock, one of which can seen below. They are not very deep, 1 mm at most. Possibly they were used to fix the stock in position during scale mounting.