Despite our teachers’ valiant efforts, most of us rely on calculators for even basic computations—and we can thank inventors such as Cyrus G. Spalding for preventing us from many math-induced headaches. On Jan. 13, 1874, Spalding received his first patent for the Spalding Adding Machine, also known as the “Surprise Adder.”
This elegant machine had a wooden box and featured a clock hand on its face. The clock hand served as an arrow on a wheel for computation of units 0–99. It was attached to a ratchet wheel inside the box. The user relied on nine metal keys to input figures. A later patent enhanced the Spalding Adding Machine with an additional wheel for adding hundreds.
The machine’s instructions promised addition with “unerring accuracy” and “surprising rapidity,” particularly once the user had mastered operating the adder while simultaneously performing mental computations.
Only a few hundred Spalding Adding Machines were manufactured, and it’s estimated only eight remain in existence today. In 1898, the Surprise Adder sold for $12.50. Today, eBay addicts pay upwards of $3,000 for this collector’s item.
Spalding’s invention was surpassed by the Burroughs Registering Accountant, a printing adding machine that remained a staple in offices until the mid-20th century, when accountants began favoring the 10-key adding machine. (Nowadays, they like Excel spreadsheets.)
Next time you balance your checkbook, give thanks to Spalding and his cohorts, who paved the way for writing mildly dirty words on your calculator in junior high—not to mention those games you used to play on your graphing calculator.
Tech Time Warp is a weekly feature that looks back at interesting moments and milestones in tech history.