William Brydone Jack was born on November 23, 1817, in Trailflatt, Tinwald, Scotland.

He was a mathematician, astronomer, and professor. He was educated at the University of St. Andrews, Scotland. In 1840, he was appointed Professor of Mathematics and Natural Philosophy at what was then King's College (later the University of New Brunswick, 1851) in Fredericton, Nova Scotia. He also designed a small wooden observatory which became operational in 1851. In 1855, William Brydone Jack, together with Dr. J.B. Toldervy, determined the longitude of Fredericton using the exchange of telegraph signals with Harvard College Observatory. This was the first precisely determined longitude in Canada. In 1861, he became the University of New Brunswick's first surveying professor and its second president (1861-1885). He introduced a course in civil engineering and surveying. The Brydone Jack Observatory was marked by an official plaque in 1955 which identified the building as the "First Astronomical Observatory in Canada."

In 1844, he married Marian Ellen Peters (1825–1858). In 1859, he married Caroline Amelia Disbrow (1829–1910). He died on November 23, 1886, in Fredericton, Nova Scotia.