Invented by the French mathematician Henri Genaille in the 19th century, the Genaille Lucas rods provided a simpler method for doing complex multiplications than with the Napier's rods. Genailles system consists of eleven wooden, metal or cardboard rods with wich small of large nummers can be arranged. The multiplication is done by following the lines ot the triangles from left to right. Detailed explanation
Unical Tables book
The Unical (UNIversal CALculator) is a heavy and huge tables book (27 x 23 x 12 cm.) containing many tabs with thousands of multiplications and percentages. Manufacturer is Jean Bergmann of Frauenfeld, Switzerland who began this work in 1910. In the editions after 1926 Bergmann included a small mechanical Correntator adder in the heavy backside of the book. One part of the book could stand up for ease of use because of a rigid cardboard flap.
Logarithmic tables
Booklet with logs and percentages tables which had to be used by everyone who has to do calculations in the pre electronic calculator era.
Paper Euro to Guilders and v.v. Calculator
As soon as the Euro was introduced in Holland, banks, oil companies and supermarkets distributed paper slide rules for converting Guilders to Euros and vice versa among their clients. Simultaneous conversions by pulling the slide upward. In two windows conversions werd displayed in increments of 15, 25, 50, and 250 from 0.10 to 95.00 on one side and from 100.00 to 300.00 on the other side. Tens of thousands of these cardboard converters were given (and thrown) away. Now it is a collector's item.
