Mathematician. Ivory was born in Dundee, the son of a watchmaker, and educated at the Universities of St Andrews and Edinburgh, where he studied mathematics and theology, with the intention of joining the church. However he decided to concentrate on mathematics and returned to Dundee as a teacher at the High School. For a time he became manager of a flax spinning company at Douglastown near Forfar and then, in 1804, was appointed Professor of Mathematics at the Royal Military College, Great Marlow (which later became Sandhurst), where he was a colleague of William Wallace (1768 - 1843). Together they built on the work of the French mathematician Laplace.
Ivory resigned in 1816 due to ill-health and continued his mathematical research while living simply in London. His difficult personality led him to quarrel with many of the British scientific establishment. Despite this, he was elected a Fellow of the Royal Society (1815), was awarded the Copley Medal (1814) and the Royal Medal of the Royal Society (1838). Ivory was honoured by many foreign scientific societies and was knighted in 1831.
Ivory worked in applied mathematics, notably the gravitational attraction of ellipsoids, the shape of self-gravitating rotating fluid bodies, atmospheric refraction and the orbits of comets. He wrote an influential article on equations in the Encyclopaedia Britannica.
Ivory bequeathed his library to the city of Dundee.
