Theodore Strong's mother was Sophia Woodbridge, and his father was Joseph Strong who was a Congregational minister. In fact Theodore was not brought up by his parents but by his uncle Colonel Benjamin Ruggles Woodbridge. This was basically a children sharing arrangement, for Theodore's parents had a large number of children while his mother's brother had no children of his own. Theodore was educated by clergymen in the area who prepared him to enter Yale in 1808. The only part of his education which the clergymen had failed to bring up to the necessary standard was, rather ironically, mathematics. However Strong was well capable of making up for the deficiency in his education in this area and was soon winning prizes in the subject.
It was Benjamin Silliman, who taught at Yale between 1802 and 1853, who did much to influence Strong. Silliman was a chemist whose work in the experimental and applied sciences made a large contribution to these subjects reaching a sound standing in the United States. While at Yale he founded the American Journal of Science and Arts which later changed its name to the American Journal of Science. Strong was persuaded that chemistry was the subject for him principally through the inspiring influence of Silliman. However Strong was also much influenced by Timothy Dwight, president of Yale from 1795 to 1817. Dwight, a theologian and poet, had pervasive effects on Yale including the modernization of the curriculum. Dwight organised debates for the senior students and Strong afterwards said that it was Dwight's example during these debates which showed him how to think and argue logically. In fact Strong did not follow his intentions in chemistry for Dwight recommended him as a mathematics tutor at Hamilton College.
Hamilton College, named after the statesman Alexander Hamilton, began as an educational establishment in 1793 when missionary Samuel Kirkland founded the Hamilton-Oneida Academy. The academy was meant to bring the children of the Oneida people and of white settlers together in an environment of learning and cooperation. Though only a small number of Oneidas enrolled, the academy lasted for 18 years. In 1812 the college was chartered as Hamilton College, the third institution of higher education to be established in the state of New York, and employed Strong from this time. Four years later, in 1816, Strong was appointed as Professor of Mathematics and Natural Philosophy at the College. He married Lucy Dix, who was from Boston, in 1818; they had seven children.
After gaining a reputation as an excellent Professor of Mathematics, Strong was offered several professorships. He declined them all until he was offered such a position by Rutgers College, which had until a year of so earlier been Queens College. The Dutch Reformed Church founded Queens College as private college in 1766. The college struggled to survive in the years after the American Revolution and was closed several times in the early 1800s. It was renamed Rutgers College in 1825 after the philanthropist Colonel Henry Rutgers and Strong taught there as Professor of Mathematics from 1827 until 1863.
Strong was a competent mathematician who provided a good foundation for American mathematics to become established. He was not in any sense in the forefront of mathematical research, being in no position to reach the standing of European mathematicians of the time. It was natural that American mathematicians of this period should be influenced by British rather than Continental mathematics and this largely disadvantaged the Americans since English mathematics was still too strongly influenced by Newton's approach to the calculus. Strong, however, was more influenced by the approach of the Scottish mathematicians who advocated the Continental approach to the calculus. Matthew Stewart had made some conjectures on the geometry of the circle which were proved by Glenie in 1805. Strong, however, was not aware of Glenie's work and in 1814 he published his own proofs of Stewart's conjectures.
Another Scottish mathematician who was working on geometry was William Wallace. He advocated the Continental approach to the calculus in his article Fluxions which appeared in Encyclopaedia Britannica in 1810 and in his article Fluxions for the Edinburgh Encyclopaedia which was published in 1815 he used Leibniz's differential notation. He was therefore the first to write an English treatise on the calculus using differential notation and it was around this time that Strong began to build up a library of Continental texts. The use of Leibniz's approach, as developed by Laplace and Lagrange, was used by Strong in his papers from about 1825 onwards so he participated actively in the introduction of the continental approach to differential and integral calculus into America. The article  contains sections entitled Strong's contributions to mathematical education and Strong's mathematical work which illustrate his contributions. In total Strong published two books, thirty-three articles, and numerous problems.
Perhaps we should say a little about these two books. The were A treatise on elementary and high algebra (1959) and A treatise on the differential and integral calculus (1869), the second appearing in print shortly after his death. Hogan writes :-
It is not clear what Strong intended these books to be. they follow the format of a text-book, but both contain some of Strong's original mathematical research, which was unsuitable for a novice. Both these books had limited circulation and negligible impact.
Among the honours which Strong received was election to the American Academy of Arts and Sciences (1832) and the American Philosophical Society. He was a founder member of the National Academy of Sciences (United States) when it began in 1863.
Article by: J J O'Connor and E F Robertson