Understanding the Add-A-Mite Mechanical Pocket Calculator

Hi there! As an avid collector and historian of vintage calculators, I wanted to walk you through the rather remarkable, yet mostly forgotten early pocket calculator called the Add-A-Mite. Made in the early 1950s using intricate miniature metal components, it boasted an incredibly compact form for its time.

In this piece, I‘ll provide some historical context on why Add-A-Mite was special when it arrived, break down how its clever mechanical guts actually worked, analyze why it ultimately failed commercially, and reflect on its broader influence. There are some neat photos mixed in showing Add-A-Mite‘s visually striking design.

So whether you‘re an engineering tinkerer interested in early geared devices, or just have appreciation for industrial design evolution, read on for an enlightening inside look!

Calculating Before Computers

To start, let‘s orient ourselves on the state of calculation machinery prior to Add-A-Mite‘s debut…

For most of human history, arithmetic aids were restricted to manual tools like the abacus. But starting in 1600s Europe, pioneers like Blaise Pascal and Gottfried Leibniz conceived the first true "calculating machines" using successive gear ratios – enabling math far faster than human cognition.

Table: Key Early Calculating Devices

DeviceOriginKey MechanismOperations
Pascaline1642Stepped drum wheelAddition/Subtraction
Leibniz Wheel1673Stepped drum wheelMultiplication/Division
Thomas Arithmometer1820Stepped drum wheelAddition/Subtraction
Odhner Arithmometer1873Pin wheelMultiplication/Division
Millionaire Calculator1893Pin wheelFour standard arithmetic

This wave of mechanical innovation laid the foundation for more versatile 20th century calculators used in business and engineering. But prior to electronics, size and complexity of the 1,000+ precision parts needed posed limits.

Could a calculator be made small enough for an ordinary shopper‘s pocket yet retain accuracy? Sacramento inventor Sahn K. Lowe would attempt this unprecedented feat.

Engineer Turned Inventor

Sahn Kempton Lowe (1891-1966) led an early career in electrical engineering and naval radio operation during WWI prior to becoming a prolific inventor in 1920s California. He served as lead design engineer on mass communication systems for Mackay Radio and Telegraph Company.

This telecommunications expertise honed Lowe‘s talents of conceiving complex mechanical and electromechanical instruments. It perhaps also spurred applying such systems toward everyday problems.

While his earlier inventions like the EZ-Out Weeder tool and Lo-Lite auto headlight focused more on utility than technological innovation, the pocket calculator Lowe envisaged next would require true outside-the-box thinking.

Conceiving the "Add-A-Mite"

Marketed as the "Add-A-Mite Pocket Calculator", Lowe filed his formative patent application in June 1950. This outlined a device with the following key specifications:

  • Dimensions: 2.5 inches x 3 inches x 0.5 inches
  • Weight: Less than 3 ounces
  • Materials: aluminum, steel and brass
  • Pricing: $2 retail

To achieve this unprecedented compactness, Lowe designed Add-A-Mite around two tiny concentric wheels…

The inner wheel represented cents from 0 to 99, while the outer represented dollar digits up to 25. Each increment on the wheels engaged a precision-milled gear tooth, enabling incremental rotation via a dial on the side. Carry propagations were built-in when traversing from 99 to 0.

Production required highly specialty manufacturing capabilities – which brings us to the company who commercialized Add-A-Mite.

Monogram of California

Founded in San Francisco in 1903, Monogram initially focused on engraving, embroidering and manufacturing custom name plates and insignias. By the 1940s, Monogram had expanded into machining small appliances and jewelry items under the brand name "Cutie Pie".

This established parts fabrication expertise made Monogram a prime partner to translate Lowe‘s Add-A-Mite concept into reality. Their trademark level of miniaturization fit perfectly.

With patents finalized in late 1953, Add-A-Mite went into full production targeting a 1954 release at select California retailers. Advertisements boasted “a mechanical brain the size of a half dollar!”

But how useful a “brain” was it in practice? Let’s analyze the real-world functionality.

Promises and Pitfalls

I was able to get my hands on an original Add-A-Mite recently to share some thoughts from a user perspective…

At a high-level, the execution of the core adding/subtracting function through the dual wheels and rotating dial works reasonably smoothly. The craftsmanship and quality of materials provides a definite sense of precision.

However, several major flaws become quickly apparent:

  • The tiny number fonts make discerning readings difficult absent good lighting
  • No hard stops or locking mechanisms means discs slip often, disrupting operation
  • Little tactile feedback provided apart from occasional gears snapping

In essence, while a remarkable feat of both electrical engineering and manufacturing, Add-A-Mite delivered quite poor usability. It demands extensive care and patience for routine adding/subtracting.

This explains why even priced economically at just $2, it simply could not compete with traditional slide rules or basic four function desk calculators of the period.

Lasting Influence

Within just 2-3 years of its release, the Add-A-Mite had disappeared from any retailer shelves or advertisements. As an actual product, it was an outright failure and quickly forgotten as superior portable calculating tools like the Curta arrived.

However, Add-A-Mite deserves credit from a technology history perspective…

It represented one of the very first attempts to rigorously miniaturize an intricate mechanical calculator while retaining completeness and precision. The underlying vision of a pocket-portable calculator for the masses was prescient.

Indeed Add-A-Mite‘s compact concentric wheel layout directly informed a far more successful successor – the Vest Pocket Adding Machine of 1958. This utilized similar dual wheels for dollars/cents, but crucially added locking stops and hard resets.

In that lens, while a commercial bust itself, Add-A-Mite demonstrated a crucial proof of concept for portable mechanical calculators. It pioneered user expectations and manufacturing techniques that evolved into many later successes.

So while you won‘t find an Add-A-Mite assisting any shoppers today, remembering its story provides a fuller picture of technology refinement. Necessity is often the mother of invention – but market misfires frequently pave the way too!

I hope you enjoyed this inside look at a little-known calculating curio. Let me know if you want to learn about other unique mechanisms from history!

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