Slide rules
Alro 500N
AL-RO was a company founded in the 1930 by Ir C.J. Dussel & A. Pasveer. Their uniqueness of the circular slide rules was the metal case, which not only protected the metal case, but also acted as a stand for desktp use. At the end of the 1950s the company stopped producing the circular slide rules.
The Oughtred Society made a special article about these circular slide rules in 2006.
The Alro 500N has on the outside the turnable scales N2 and N and on the inside N N2 and R. The diameter is 13cm. The metal is aluminium.
This item is in a good, but used condition
If you want pictures in a better resolution, don't hesitate to email me
