[1] Born on St. Patrick's Day in Newtownstewart, County Tyrone, Ireland, the eldest son of Rev James Maclear and Mary Magrath.

Maclear had a keen interest in amateur astronomy, and would begin a long association with the Royal Astronomical Society, to which he would be named a Fellow.

In 1833, when the post became vacant, he was named as Her Majesty's Astronomer at the Cape of Good Hope, and arrived there aboard the Tam O'Shanter with his wife and five daughters, to take up his new duties in 1834.

[3] The Maclears and Herschels formed a close friendship, the wives drawn together by the unusual occupations of their husbands and the raising of their large families.

He caused a beacon to be erected on top of Table Mountain which was used as a triangulation station for the checking of de Lacaille's arc measurement.