15th January 1717

Maths genius Matthew Stewart is born

Matthew Stewart followed his father into the church, but didn’t last long. After attending school, he went up to the University of Glasgow in 1734 and, according to the Transactions of the Royal Society of Edinburgh, published in 1788, “his studies were prosecuted with diligence and success”.

He initially enrolled to study maths, which brought him into contact with doctors Hutcheson and Simson, “with the latter of whom,” says Transactions, “he soon became very intimately connected [when] the particular direction of his talents was probably observed by his master before it was perceived by himself… he lived in the closest intimacy with that excellent mathematician, and was instructed by him in, what might not improperly be called, the arcana of the ancient Geometry.”

Professor of mathematics

Stewart and Simson set about improving on the discoveries of Fermat and Halley among others. However, despite his interest in maths, Stewart’s father, a vicar, remained keen for his son to become a member of the clergy, and Stewart enrolled to study divinity at the University of Edinburgh.

He was licensed by the Church of Scotland in 1745, became a minister in Dumbartonshire in 1746 and left to become a professor of mathematics, back at the University of Edinburgh, in 1747. His contribution to our understanding of mathematics over the coming years was greater than that which he had contributed to the church.

Astronomical calculations

Stewart’s theorem, named after him, is a way of calculating the lengths of the sides of a triangle that sits within a larger triangle, and he calculated the distance between the sun and Earth to a fair accuracy for his time at 119 million miles (modern calculations put the actual distance at around 93 million miles). He also provided a geometrical solution to Kepler’s problem, which allowed for accurate predictions of the positions of planets, taking into account the effect of nearby objects.

His calculation of the sun’s distance from Earth was one of his last great works. As the Transactions of the Royal Society of Edinburgh explains, “soon after the publication of the Sun’s Distance, Dr Stewart’s health began to decline, and the duties of his office became burdensome to him. In the year 1772, he retired to the country, where he afterwards spent the greater part of his life, and never resumed his labours in the University.”

Stewart’s son, Dugald, started to lecture on his father’s behalf, and Matthew Stewart died on 23 January 1785, aged 68.