In this booklet of 80 pages, E. Peraux, a trader from Nancy, presents his two-slide rule made by Tavernier-Gravet.
On the back of the book, the price of slide rules in 1893: an ordinary rule (25 cm) is worth 7 francs, the Peraux rule of the same length 15 francs,
and that of 50 cm is worth 80 francs, considerable price at that time.
