William Henry Hart – Complete Biography, History, and Inventions


William Henry Hart – Complete Biography, History, and Inventions

Who was William Henry Hart?

William Henry Hart was an inventor, watchmaker, jewelry store owner, and proud incorporator of the Spiritual and Liberal Association. From his birthplace in New York to his final resting place in the American utopian socialist town of Los Mochis, Sinaloa, Mexico, he lived a colorful life. He’s best remembered for Hart’s Mercantile Computing Machine, which helped advance calculator technology in the 19th century.

William Henry Hart

Early Life

William Henry Hart was born in the state of New York in 1829. Little is known about his childhood but as an adult, he and his family lived in Maysville, Wisconsin. He married Elizabeth Davidson, from Pennsylvania, in 1850. Hart and his family moved to Kirksville, Missouri from Maysville, Wisconsin in 1867.

Quick Facts

Full Name
William Henry Hart
Net Worth
Place of Birth
New York
Fields of Expertise
W. Hart Jeweler, Hart & Miller, Hart’s Jewelry Store, and Hart & Son
Mercantile Computing Machine


Hart spent much of his career as a jewelry store owner. Later in life, he spent his time inventing various devices. The end of his life was in the Liberal and Spiritual Association.

Jewelry Store Owner

In Kirksville, Hart opened a jewelry store in the square, doing business as W. Hart Jeweler. He ran for City Council and lost in 1874. Hart entered a partnership with Albert Dutcher in 1875 and then sold his share of the firm to Dutcher. Because of declining health, he decided to spend more time outdoors.

The 1880 Federal Census shows Hart’s occupation as a watchmaker. By 1886, however, Hart went back to the jewelry business in the firm of Hart & Miller. He was later the owner of Hart’s Jewelry Store.

In December 1890, a fire not only destroyed Hart’s store but also took the life of his son, Volney. William Hart himself barely survived with a broken right leg and burns on his hands and face. In 1892, Hart opened Hart & Son, a jewelry store he owned with his son Lawrence who later became an osteopath.


William Henry Hart was a very good mechanic and prolific inventor because he had at least 13 patents for various instruments and devices. His most notable patent was for Hart’s Mercantile Computing Machine. This calculator appears to have been commercially successful, with reports of thousands behind manufactured.


In 1884, William Hart and his wife were two of the incorporators of the Spiritual and Liberal Association. This association believed that certain spirits of the deceased manifested themselves and, in some instances, conversed with their friends on earth. While he left Kirksville and the United States behind, it’s unknown whether he changed his religious and social beliefs as he moved to Los Mochis, Sinaloa, Mexico.

What Did William Henry Hart Invent?

Hart had at least 13 patents to his name at the time of his death. Many of them, unfortunately, don’t appear to have ever been manufactured. Here are a few examples of patents that may have never left the design phase:

  • Second-hand holder and screw-end finisher (US patent 264532)
  • Five separate graphophone-reproducers (US665601, US648406, US644981, US651308, and US817062)
  • Three clock-escapements (US33990, US326292, and US106815)
  • Hammers (US217101)
  • Ruby-pin and pallet setter (US264533)

Hart’s Mercantile Computing Machine

Hart’s Mercantile Computing Machine, US patent 199289, was patented in January 1878. According to the Smithsonian National Museum of American History, the local Kirksville Missouri Democrat newspaper claimed on July 26, 1888, that Hart sold over 3,5000 computing machines. One machine is still on display at the Smithsonian.

The calculator consisted of three concentric brass discs, a brass marker, a steel stop, and a long wooden handle with a pointer coming down from its end. Any hundreds value in the sum carries to the second set of holes, which were used to add hundreds’ and thousands’ places. When the total exceeded 99, a hand like the shorthand of a watch automatically advanced one to indicate the hundreds’ value. This allowed it to indicate sums up to 9,999.

William Henry Hart: Marriage, Divorce, Children, and Personal Life

While little is known about William Henry Hart’s childhood and personal life, he was married once, had eight children, and appeared to have been a successful businessman during his lifetime until he died in 1907. 


William Henry Hart married Elizabeth Davidson in 1850. He was approximately 21 years old when he married and Elizabeth, born 1831, was 18 or 19 years old. She was from Pennsylvania and the couple remained married until, 44 years later, Elizabeth died.


William and Elizabeth Hart had eight children: Emma Delilah (1851-1928), Rosalie (1853-1942), Henry (1855-1930), Sarah Sadie (1861-1924), twins Lawrence and Clarence (b. 1866), Volney (1872-1890), and Waren (1873-1877).


After the death of his wife on January 27, 1894, Hart continued his work and inventing, but eventually, he left Kirksville and the United States. He relocated to Mexico, where two of his children, Henry and Rose, lived. Hart remained in Los Mochis, Sinaloa, Mexico (a town founded by a group of American utopian socialists), until his death on April 2nd, 1907.

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Frequently Asked Questions

Who was William Henry Hart?

William Henry Hart was a watchmaker, jewelry store owner, and inventor. He had eight children and was an incorporator of the Spiritual and Liberal Association. His most significant contribution to technology was his invention: Hart’s Mercantile Computing Machine.

What did William Henry Hart invent?

William Henry Hart invented Hart’s Mercantile Computing Machine, which was patented in 1878. It used concentric brass rings and steel components to calculate sums up to 9,999.

How did William Henry Hart invent Hart’s Mercantile Computing Machine?

William Henry Hart spent most of his life as a jewelry store owner and inventor, where he may have learned the mechanical skills necessary to invent his computing machine. He patented at least 12 other inventions during his lifetime, showing an aptitude for mechanical invention.

When was William Henry Hart born?

William Henry Hart was born in 1829 in the state of New York.

When did William Henry Hart die?

William Henry Hart died on April 2nd, 1907. He was in Los Mochis, Sinaloa, Mexico, which was founded by American utopian socialists. Two of his children, Henry and Rose, also lived in Mexico.

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