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Thomas Jefferson and his Decimals 1775-1810: Neglected Years in the History of U.S. School Mathematics

M. A. (Ken) Clements and Nerida F. Ellerton
Publication Date: 
Number of Pages: 
[Reviewed by
Charles Ashbacher
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To the modern U. S. citizen that easily computes change from a transaction and can compute the amount of simple interest very quickly, the value of a decimal system of currency is largely an unconscious given. You simply do it and get the proper result. That was not always the case. In the early years of the United States currency calculations were far more involved. As you can learn from this book, those early computations are almost incomprehensible to the modern citizen.

It is a largely unknown historical fact that Thomas Jefferson was the main political driving force behind the conversion to a national decimal monetary system. Since the country developed as separate states whose inhabitants came from different countries, the colonists brought to their states their own monetary systems as well as their systems of weights and measures. Thomas Jefferson pushed both for a national decimal monetary system as well as for a national decimal system of weights and measures. The first became law but there was so much opposition to the second that it never happened and Jefferson gave up the attempt. Fortunately, a national system of weights and measures was adopted based on the British system. Until then some states had different definitions for the value of units such as the bushel.

With very few countries using a decimal system of currency at the time, the adoption of one in the United States was a far greater achievement than is generally historically acknowledged. The colonists used the non-decimal British and Spanish systems and both remained legal tender well past the adoption of decimal currency. As the authors point out with several examples, although computations of business actions such as making change and computing interest in these systems were cumbersome, they were known, whereas decimal computations were the unknown.

School mathematics in this case means elementary school, where children learned what was then called cyphering. It was a time when education was generally reading, writing and arithmetic and was not universal. The quality of the teachers was also quite low and most of the textbooks were British, so there was additional inertia built into the system. Poor quality teachers generally abhor the unfamiliar.

This is a fascinating book for it is a combination of social, political and business history along with the mathematics. Major change is hard, a national population is very reluctant to accept even modest changes in currency and weights and measures, even when it is clearly an advantage to do so. 

Charles Ashbacher splits his time between consulting with industry in projects involving math and computers, teaching college classes and co-editing The Journal of Recreational Mathematics. In his spare time, he reads about these things and helps his daughter in her lawn care business.

​Early Moves Toward Metrication in Europe

Measurement Chaos in North America, 1780–1980

Opportunity Lost: Big Money Successfully Thwarts Thomas Jefferson’s Push for Metrication 1776–1793

Muddling Along: Opposition to Moves for Metrication, 1793–1920

David Eugene Smith’s Involvement in the Metrication Issue, 1920–1935

The Decision for Metrication, 1970

Reaganomics, Big Money, and the Crushing of the Metric Dream, 1970-1980

Why has the United States Never Achieved Metrication?.