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Wilhelm Schickard and the Revolutionary Calculating Clock

Overview

Wilhelm Schickard (1592-1635) was a German professor and Protestant minister who pioneered the design of a remarkable early calculating machine – the ‘Rechen Uhr‘ or Calculating Clock.

Developed in 1623, it was the first documented mechanical calculator and the forerunner of machines that would ultimately lead to modern computers.

Tragically, the only examples ever built were destroyed in fires and accidents during Schickard‘s lifetime. So while an influential advancement for its time, the world soon forgot this incredible early calculating device.

It wasn‘t until the 1950s when Schickard‘s letters and sketches were re-discovered that his technical brilliance was revived. And with modern reconstructions in 1960, the operation of this revolutionary 17th century Calculating Clock has been revealed in full detail.

Join me as we rediscover the life of Wilhelm Schickard, the origins of his ambitious invention, how this pioneering calculator worked, and the immense influence it had on computing history…

The Polymath Who Dreamed of Thinking Machines

Wilhelm Schickard was born in 1592 near the southern German city of Tübingen where he would later become a prominent professor. As a young Lutheran minister and Hebrew scholar, Schickard displayed an exceptional aptitude for languages, theology, law, astronomy, mathematics and surveying.

When Schickard met the acclaimed astronomer Johannes Kepler in 1617, Kepler immediately recognized in the 25 year old minister ‘‘an excellent talent" with a “massive intellect". Despite their age difference, the two formed a close and lengthy friendship. Kepler encouraged Schickard’s interest in scientific instruments while Schickard assisted Kepler with illustrations, cared for his son in Tübingen and helped with Kepler’s astronomical calculations.

In 1619, Schickard’s prodigious talents saw him appointed as a mathematics and astronomy professor at the University of Tübingen. He continued lecturing in varied subjects including Hebrew, geography and law, while tinkering with inventions from astronomical telescopes to land surveying equipment.

But Schickard’s most revolutionary invention began in 1623 inspired by Kepler’s enthusiasm for an emerging mathematical innovation – logarithms.

The Tedious Calculations of Astronomy

First published by Scottish mathematician John Napier in 1614, logarithms provided an ingenious way to turn difficult multiplications into much simpler additions. Kepler became an ardent enthusiast of Napier’s breakthrough method. However, while logarithms dramatically sped up mathematical work, creating the required tables still involved laborious hand calculations.

It was while assisting Kepler with computing astronomical tables in 1623 that Schickard conceived of an incredible machine to mechanize this repetitive process – the ‘Calculating Clock.’

In September 1623 he wrote to Kepler:

"I have tried to discover a mechanical way for performing calculations, which you have done manually till now. I constructed a machine, which includes eleven full and six partial pinion wheels, which can calculate automatically, to add, subtract, multiply and divide…"

When Kepler asked for a copy of the device to aid his ongoing astronomical calculations, a technician named Johann Pfister set about constructing another machine. But tragedy struck just months later as Schickard wrote again to Kepler in early 1624:

"…when the work was half finished, yesterday night a fire burst out and everything burnt out, as Maestlin informed you. I take this loss very heavily…"

While the original prototype and the copy intended for Kepler were both destroyed by fire, Schickard‘s letters and drawings remain as the only record of this visionary calculating device centuries ahead of its time.

Bringing The 17th Century Digital Calculator To Life

Schickard‘s Calculating Clock incorporated a number of remarkably advanced features for the technology of his day:

Key Components

  • 3x Vertical Napier‘s Rod Cylinders – for number entry and multiplication
  • Movable Sliding Plates – selection windows for partial products
  • 6x Result Dials – separate displays for intermediate values
  • 6-Digit Adding Mechanism – core adder with automatic carry

Innovations

  • Napier‘s Rod Integration – unique adoption for multiplication
  • Reversible Adder – subtraction as well as addition built-in
  • Overflow Detection – automatic error notifications

From Schickard‘s notes, the adding mechanism bears further examination for its revolutionary design:

Component Purpose Innovation
10-Tooth Wheel Digit Rotation Reversible
1-Tooth Wheel Automatic Carry Novel Integration
Intermediate Catch Wheel Next Position Transfer Error Reduction

The combination of these pinion gears enabled both addition and subtraction in the one mechanism while minimizing issues with gears slipping.

This adding device foreshadowed all subsequent calculator design right up to the first desktop computing machines in the 1940s. Schickard‘s genius was centuries ahead of its time!

The Legacy of A Pioneering Machine

While the Calculating Clock itself was soon lost to history, Schickard‘s ideas went on to inspire others working at the cutting edge of mechanical calculation:

Blaise Pascal patented a calculator in 1642 that built upon Schickard‘s work with Napier‘s rods and reversible adders. But it lacked features like overflow detection.

Gottfried Leibniz created his own advanced calculating machine in 1673, crediting Schickard‘s lost device as an inspiration after reading of it in scholarly letters.

Charles Babbage pursued his famous 19th century Difference and Analytical computing engines likely influenced by accounts of the pioneering work of Schickard two centuries earlier.

And Howard Aiken, creator of the landmark Harvard Mark I computer in 1944, would title his thesis on mechanical calculation "Wilhelm Schickard – An Unrecognized Pioneer".

Through articles like Aiken‘s, Schickard‘s legacy was revived in the 1950s as his 1623 Calculating Clock earned recognition as the very first documented mechanical calculating device – restoring his place as a true pioneer in computing history.

The life of Wilhelm Schickard reminds us that genius may lie undiscovered or be forgotten by time. Yet even centuries later, new generations can still be touched and inspired by inventions from the past.

While vanishingly few examples of his namesake Calculating Clocks remain today, Schickard‘s vision for mechanized calculation sparked a flame that would grow into the modern digital computer revolution.