Slide Rulers

…inherited from my father-in-law, used in the 1930s, made by a Vienna factory (IV. district, Favoritenstraße 16). 

No. 3 in my series “MyFamilyhistory”, inspired by Lathyrus.

Slide rulers were effective tools in the time before pocket calculators came into use. We used slide rulers at school in the early 1970s, and my first pocket calculator cost 200 DMarks in 1974. That was a lot of money, but a great improvement.