Solomon Pool’s Adding Machine

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Solomon Pool’s Adding Machine

Adding machines are some of the most fascinating inventions and are important too. The early inventions were instrumental in forming the way that mathematics — and other subjects — were able to be carried out. There are many different types of adding machines that have been invented through the years, some which became popular and successful, and others which did not. Solomon Pool invented an adding machine that could add figures up to 999. Read on to learn about Solomon Pool and his adding machine.

Early Life

Solomon Pool
Pool became President of the University of North Carolina in 1869. He was a licensed preacher as well.

Solomon Pool (see biography of Solomon Pool), was born on April 21, 1832, at Elmwood on the Pasquotank, his family’s plantation near Elizabeth City, N.C. Pool was an educator, the University of North Carolina president, and a clergyman. He was a member of one of the most prominent families in Elizabeth City, N.C., in the 19th century. His father, also named Solomon Pool, was a wealthy slaveholding planter who lived in Pasquotank County. His mother, Martha Gaskins Pool, died when Pool was five. Since his father died before his mother, Pool was raised by George Decatur Pool, his older brother, who became an active Republican. Pool’s other brothers were John, who became a U.S. senator, and William Gaskins, who was a physician.


Pool entered the University of North Carolina when he was seventeen and graduated with honors in 1853. Later that year, he became a mathematics tutor at the university, and in 1856, he received an honorary alumni master’s degree. He was promoted to adjunct professor of math in 1861 and remained in that position until 1866. He then took a leave of absence to serve as U.S.S. deputy appraiser in N.C., a more lucrative position that paid $5,000 per year.

In 1869, Pool became president of the university for $1,500 annually and was allowed to keep his appraiser’s job as well.

It’s interesting to note that, while his father was a slaveholder, Pool rejected slavery and angered his contemporaries with his notions of egalitarianism.

Pool was a licensed Methodist Episcopalian preacher who preached at the Chapel Hill Chapel monthly, as well as a number of other venues as requested.

Marriage and Children

In 1856, Pool married Cornelia Kirkland. The couple had six sons and two daughters.

Pool became paralyzed while preaching at a revival in 1896. Though he recovered partially, his health remained poor and he died five years later.  

Pool’s Adding Machine

In 1873, Solomon Pool of Chapel Hill, North Carolina (at the time a principal of a school in Cary, N.C.), patented a small and handy adding machine (US patent 143184) (see image below).

Solomon Pool
Solomon Pool’s adding machine was designed to add up to 999, but indicated that additional rings for thousands (or any number with a power of ten) could be employed.

The adding machine of Pool is a cylindrical adding device with a numerical capacity of 999 (although Pool mentioned that a ring for thousands, or rings for any number that represents a power of ten, may be employed). The input and zeroing of the device was made by rotating of the rotary plate B, b, b’, which could be rotated in both directions.

The tens carry mechanism was implemented by means of a pawl, which caught a ratchet-tooth, and carried the motion to the next ring.

Frequently Asked Questions

Who was Solomon Pool?

Solomon Pool was an educator who became the President of the University of North Carolina. He was also a cleryman.

What did Solomon Pool invent?

Solomon Pool invented an adding machine which could add numbers up to the sum of 999. It was a circular device which was operated by rotating a plate.

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