Set of 3 slide rules and a proportions compass. One of them, FABER-CASTELL (Germany). Central Europe, ca. 1920-30's.

Set of 3 slide rules and a compass of proportions. One of them, FABER-CASTELL (Germany). Central Europe, ca. 1920-30's.
Metal, wood and bone.
In their original boxes.
Boxes have flaws and flaws.
Measurements: Measurements: 2,5 x 31 x 6 cm (the largest).

Lot of technical drawing instruments from the 1920's: three slide rules and a proportions compass. In their original cases, some lined with imitation leather.

The Faber-Castell school supplies firm is one of the oldest German companies, having been founded in 1761. It began as a carpentry workshop founded by Kaspar Faber in Stein, near Nuremberg. Subsequently, one of his descendants, Lothar Faber, made the pencil the world's first branded writing implement. His factory in Geroldsgrün in northern Bavaria initially produced school slates, but later became one of the most important producers of slide rules. The A. W. Faber product range gained worldwide recognition thanks to the international sales network that Lothar successfully established over the course of a few decades.

The slide rule has several movable numerical scales that facilitate the quick and convenient performance of complex arithmetic operations. Its scales have been modified in order to be adapted to specific fields of use, such as civil engineering, electronics, construction, aeronautics and aerospace, financial, etc. Their historical evolution had a high point that coincided with the advent, at the beginning of the last third of the 20th century, of the first electronic calculators and the primitive personal computers. From the middle of the 19th century until its decline in the last third of the 20th century, its use was more or less widespread in the areas of engineering, administration and pre-industrial craftsmanship. In the first decades of the 20th century its use was so widespread that there was no engineer who did not have access to a slide rule. The oldest models were made on scales engraved in wood, brass, bone, like the ones shown here.