Special Sliderules

ALRO Circular Slide Rule   ALRO 200R. Made in The Hague, Holland. Circular slide rule consisting of two discs, the outer one of which rotates. It is set in a metal box which, when opened, can double as a desk stand. It has a spiral log scale printed on paper on the lid.

Aristo MultiTrig   Artisto MultiTrig Slide Rule Table Model. Made in Germany by Dennert and Pape, Hamburg. Materials: Astralon and Plexiglass. The factory produced all kinds of slide rules and scientific precision instruments for more than a century. Among others: the DR-2 Flight Computer. Production was abandonned in 1978.

E6-B Flight Computer   The E6B is a form of circular slide rule used in aviation. They are mostly used in flight training, but many professional and even airline pilots will still carry and use their E6Bs. E6Bs are used during flight planning (on the ground before takeoff) to aid in calculating fuel burn, wind correction, time en route, and other items. In the air, the E6B can be used to calculate ground speed as well. The back is designed for wind correction calculations, i.e., determining how much the wind is affecting your speed and course. The circular slide rules are usually made out of aluminum and plastic.

Mercator Flight Computer B 4 HS   This is a very interesting and sophisticated slide rule for various Aviation, Flight, Navigation and Aero-technical usage. It is an aluminum slide rule with charts and with a circular slide rule which is operating as the cursor too. Made by the Mercator Computer Company in Alkmaar, Holland. Features: One side: 10 inches rule & 25 cm rule Chart for Ground speed/Glide Path Angle/Descent Scale Circular Disc with many scales (Airspeed, Altitude, Air Temp., Minutes, Weight... and more).

Handy-Ready     Three handy-ready pocket slide rules in leather cases. From left to right: Aristo single sided, Faber Castell with an addiator on the back side and Aristo 803.

Ecobra 1600   Ecobra 1600. Metall Slide rule. Collector's item.Very robust. Made of aluminum.

Otis King's Pocket Calculator Cylindrical slide rule with helical scales, made in England by Carbic Ltd., London 1921-1972. Suitable for general and specialized arithmetic. The device has a telescopic design and consists of four parts: holder, bottom scale, movable cursor and top scale. Rather easy to operate for those who are (were) able to work with normal lineal slide rules.

Faber - Castell Famous and much used slide rule from the well-known manufacturer Faber-Castell. This extensive slide rule was very useful for complex calculations to be performed by engineers and technicians on a daily basis.

Circular Calculating Discs   Some more circular slide rules for various purposes, e.g.a modern circular plani-calculating device for amateur astronomers, a curvimeter for obtaining distances from maps and a black rotating technical calcudisk for calculating capacitors.

Various old slide rules Three rather old slide rules in cardboard holders. Above an original Raphoplex made of white plastic. One side only but very precise. In the middle a wooden Nestler useable on both sides. Below a wooden Faber 'Castell' with various tables on the back side.

Specialized technical slide rules   In most technical fields where complex calculations are necessary all kinds of specialized slide rules were in use, where now scientific pocket calculators are dominant. To the right four technical slide rules for gasflow, temperatures and pressure calculations.

Monsanto Sliderule     Small but very powerful sliderule for advanced use by scientists and engineers. Besides a circular slide rule it provides a periodic table of the elements at the backside. From within a small card can be pulled out with energy, pressure. velocity and flow rate conversion tables on one side and volume, length, mass, area and force tables on the other side. The Monsanto is a wanted collector's item.