Orphaned son of a major in Charles XII's army, I was educated by the Bishop of Linkoping; intending to study law to be a civil servant, I was sidetracked by my interests in mathematics and physics.
In 1727, at age 29, I was given a scholarship that funded my travel throughout Europe, where I studied under Christian Wolff, Jacob Bernoulli, and B. Le B. de Fontenelle.
While still traveling, I was appointed Professor of Mathematics at Uppsala and eventually became the personal tutor to the Crown Prince.
In physics, I corrected Newton's ideas on the refraction of light, which made it possible to construct an achromatic lens.
Almost unknown or forgotten as a mathematician because of my unwillingness to publish my ideas, I did help publish two books, a Latin version of Euclid's Elements in 1741 and an annotated translation of Peter van Musschenbroek's Elementa Physica in 1747.
I preferred geometric solutions to algebraic ones, as demonstrated in my solution of Euler's 1745 problem on reflecting light; other mathematicians had solved the problem but they used "calculatory methods" whereas my solution "merely" looks "at the figure, without calculation, goes straight to the purpose."
Answer:
Samuel Klingenstierna (1698  1765)
