The watch journal

Juvenia Arithmo: The Calculating Watch

In the 1950s, long before electronic calculators became commonplace objects, Juvenia introduced the Arithmo, a wristwatch equipped with a circular slide rule capable of performing mathematical calculations.

Accompanying this unusual watch was an illustrated instruction booklet explaining how to operate its rotating scales, with examples covering multiplication, division, logarithms, and square roots.

Original copies of the booklet are seldom seen in their entirety. Following requests from collectors and owners of similar watches, we've photographed all 11 pages of our example and made them available here as a reference to one of watchmaking's more unusual creations.

The original 11-page instruction booklet is reproduced below in its entirety. Shared in response to requests from fellow collectors and Arithmo owners, it offers a closer look at how Juvenia intended its calculating watch to be used.

The Back Cover

The back cover is equally interesting, bearing Juvenia's original insignia alongside catalogue number 100 and a printed price of CHF 1.50. These small details are part of what makes the surviving booklet such a fascinating companion to the Arithmo, offering a glimpse into how the watch was presented in the 1950s.

A mechanical calculator for the wrist

The Arithmo's defining feature is its circular slide rule, operated by the outer rotating bezel, which Juvenia referred to as the slide index. Made from what the brand described as “unbreakable glass,” the bezel rotates in both directions against a fixed inner scale, allowing the wearer to perform calculations directly on the wrist.

More than seventy years later, the original instruction booklet remains a fascinating record of how Juvenia envisioned this unusual watch being used. Preserved here in its entirety, it offers collectors and fellow Arithmo owners a rare opportunity to explore the watch's capabilities through the manufacturer's own instructions.

Explore the Juvenia Arithmo Watch

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