A Revolutionary 19th Century Calculating Device You Should Know About

Hi there! Have you ever used a hand-cranked adding machine or wondered how we calculated long before electronic calculators? Stick with me to learn about a brilliant, yet mostly forgotten early adding machine – created way back in 1873 by an intriguing Southern academic named Solomon Pool.

Overview of Solomon Pool‘s 999 Adding Machine

Solomon Pool was a mathematics professor who later became President of the University of North Carolina in Chapel Hill. Fascinatingly, he also worked as a licensed preacher on weekends!

In 1873, Pool patented an innovative mechanical adding device that could tally numbers up to 999. This may not seem remarkable today when even basic $5 calculators can handle much larger figures. However, at the time, it represented a 10x capacity improvement on existing machines.

Pool achieved this breakthrough through a clever design with stackable rings representing hundreds, tens, and ones digits. The user dialed in numbers then cranked a handle to advance the rings and add. Despite the utility of this invention, there is unfortunately no evidence Pool‘s device progressed beyond a patent into commercial production.

Nonetheless, historians view it as an important evolutionary step toward more complex calculating machines that emerged in the late 19th and early 20th centuries. So while Pool‘s name may not be instantly recognizable, his 999 adding machine deserves appreciation!

Getting to Know the Inventor: Solomon Pool

Solomon Pool came from a prominent North Carolina family that included wealthy plantation owners and politicians. He lost his mother early on and was raised largely by his older brother.

Pool graduated with honors in mathematics from UNC in 1853. He stayed at the university as a math professor before leaving briefly for a lucrative job appraising imports. By 1869, he returned to academia as President of UNC – a position that only paid $1500 a year.

Remarkably, Pool balanced multiple other pursuits:

  • Preacher – He was an ordained Methodist minister who delivered monthly sermons in Chapel Hill and other venues.
  • Philosopher – Contemporaries noted Pool‘s "philosophical bent" and rejection of prevailing notions on slavery and equality.
  • Inventor – While working as a school principal in the early 1870s, he patented his 999 adding machine.

So Pool was clearly an intelligent and unconventional thinker who explored ideas on math, machinery, morality and spirituality!

The Need Pool Was Addressing with His Device

What motivated this educated son of a plantation owner to invent a mechanical adding machine? Simply put, tedium and inefficiency!

In the 19th century, most calculations were still done manually with pen and paper. This worked for basic arithmetic, but became increasingly impractical for bookkeepers, merchants, bankers and the like as numbers grew larger. Errors were common even for trained professionals working carefully.

The few mechanical calculating aids available before Pool‘s time also had severe limitations:

  • 1617 Calculator – Could only add and subtract numbers up to 9
  • Pascaline – Handled 8-digit numbers but required tedious dial resetting
  • Leibniz Stepped Reckoner – Supported addition/subtraction of 3-digit numbers

So while revolutionary in their era, these machines were still tedious and limited for real-world use. Pool aimed higher by creating a device tailored for common tasks like tallying bills of sale, inventory counts and ledger balances – where totals often ranged into the high hundreds.

How Pool‘s 999 Adding Machine Worked

The key principles and mechanisms powering Pool‘s device were brilliant in their simplicity. As described in his 1873 patent, it consisted of three metal rings stacked vertically, representing hundreds, tens and ones [1].

The rings were numbered 0-9 and mounted on a central axis. To input numbers, the user simply rotated the rings to align digits in the appropriate columns.

Then, turning a crank handle advanced each ring by 1 unit per crank. Cleverly-designed internal pawls activated to "carry" leftward, just like how we humans handle carries between columns through manual addition.

According to Pool‘s patent, additional rings representing thousands or any other power of ten could extend capacity arbitrarily higher. But his initial implementation handled 3-digit numbers up to 999.

Sample Operation

Let‘s walk through a quick example totaling 457 + 222:

  1. Rotate rings to input 457
  2. Crank handle 4 times to advance ones ring from 7 to 1
  3. Crank handle 5 more times to advance tens ring from 5 to 0, activate carry pawl
  4. Crank once more to advance hundreds ring by 1 to 6
  5. Input 222 by rotating rings
  6. Crank handle 2 times to advance ones ring to 4
  7. Crank handle 2 more times to advance tens ring to 2, activate carry
  8. Crank again to advance hundreds ring to 7

Result: 679

It took a bit of getting used to, but Pool‘s machine dramatically sped up addition tasks compared to pencil and paper!

Technical Specifications and Context

Pool‘s 999 adding machine specs were impressive compared to earlier-generation devices:

DeviceInventorYearCapacityCarry Mechanism?
1617 CalculatorWilhelm Schickard1617Single digitsNo
PascalineBlaise Pascal16428-digit numbersNo
Stepped ReckonerGottfried Leibniz16943-digit numbersYes
Pool Adding MachineSolomon Pool18733-digit numbers (999 max)Yes

As we can see, Pool built upon previous pioneers‘ work but significantly expanded capacity through his 999 machine. This was achieved through additional digit rings and his novel carry mechanism.

Unfortunately, there is no evidence Pool progressed from patent to commercial manufacturing. But historians view his device as an important evolutionary step:

  • Provided blueprint for high-capacity, practical adding machines
  • Influenced later inventors like Dorr Felt who created first commercially-successful adders
  • Signposted path toward modern calculating tools we rely on today

So while you won‘t find Pool‘s machine behind glass in the Smithsonian, we still owe him appreciation for his incremental engineering advance!

Final Thoughts on a Fascinating Historical Figure

We covered a lot of ground here! So in conclusion, let me reinforce why Solomon Pool and his 999 adding machine deserve more name recognition.

Though his calculating contraption never made it to production, Pool made an often-overlooked contribution. In the lead-up to true commercial adding machines, he optimized features like expanded digits and carry functionality. This evolutionary step was forgotten over time but still helped pave the way for the convenient math aides we know today.

Beyond this clever invention, Pool himself was clearly brilliant yet unconventional – an ordained minister moonlighting as a college president who dabbled in philosophy! He rejected prevailing views on equality at the time so was also socially progressive.

Solomon Pool shows how innovations often combine both engineering insight and flashes of individual genius. I hope you enjoyed learning a little about this fascinating historical inventor and his ambitious early adding machine! Please let me know if you have any other questions.

[1] Pool, S. (1873). US Patent No. 143,184. Washington, DC: U.S. Patent and Trademark Office.

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