Dating to the late 1930s, this is a fine example of the Fowler Magnum Long Scale calculator, designed primarily for engineers.
At the time, it was the largest model in the Fowler range, before the Jubilee Magnum came along in 1948. Measuring 4¾" (120 mm) in diameter, it is a substantial instrument, larger than most Fowler calculators, featuring a series of concentric circular scales to make numerous calculations.

Weighing just over 430 grams in its case, it is in full working order, with the dial and pointer spinning smoothly in both directions, when spinning either control knob. In very good cosmetic condition, it has clean scales and a chip-free glass face, while the underside has a black hammer finish steel backplate, which is free of any blemishes.

The calculator comes with its original brown leather case, which is also in good condition, and includes its original 36-page instruction booklet, which, while a little worn, is structurally sound.