Circular Slide Rules & Calculators

Fowler's Magnum Long Scale Calculator




This is a single-sided calculator 4.5" dia (125mm). Supplied in a brown leather case. There are seven separate scales. Beginning with the largest in diameter, No.1, and proceeding inward.

Scale No. 1. The outer short scale, a single circle 13.5" in circumference, mainly used for multiplication and division etc., analogous to the to the ordinary slide rule.

Scale No. 2. Reciprocal scale.

Scale No. 3. Square root scale.

Scale No. 4. A scale of Logarithms.

Scale No. 5. The Long Scale. Extending round six circles. Total scale length 50" (127cm)

Scale No. 6. A scale of angles. Natural Sines and Log. Sines.

Scale No. 7. A scale of angles. Natural Tangents and Log. Tangents.