Set of 3 slide rules and a compass of proportions. Central Europe, 19th century.

Set of 3 slide rules and a compass of proportions. Central Europe, 19th century.
Steel, wood and bone.
In their original boxes.
The boxes have flaws and flaws.
Measurements: 9,5 x 30 x 4 cm (the largest).

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

The slide rule has several movable numerical scales that facilitate the quick and easy 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, finance, 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.