**John Cruickshank** was a Scottish mathematician who reformed both the mathematics teaching and the degree structure at Marischal College, Aberdeen.

- John Cruickshank's first teacher at the local school was Margaret Brown.
- It is highly likely that John would have heard about his teacher's famous relation and his fame as a lecturer and inventor of astronomical instruments.
- Certainly John became interested in astronomy and, sent to work as a herd boy, he spent the nights watching the sky and observing the motions of the planets.
- Two of the pupils that Cruickshank taught in the parish school at Ordiquhill were his cousins John and William Ogilvie.
- John Ogilvie is, however, famed as a lexicographer publishing The Imperial Dictionary (1850-51), one of the most popular dictionaries of its day.
- Returning to the life of John Cruickshank, after attending the parish school at Ordiquhill, he studied for a short time at the Grange school.
- After graduating with his M.A., Cruickshank worked as a teacher at Boharm, and as a tutor at Haddo and then at Netherdale.
- In 1817 Hamilton and Copland exchanged chairs and, on 9 July 1817, Cruickshank was appointed as "assistant and successor to Professor Hamilton", now the Professor of Mathematics.
- Although Cruickshank was appointed as Hamilton's successor, in fact it was not until 1824 that Hamilton retired completely from teaching.
- Once Cruickshank was secure in his position as Professor of Mathematics at Marischal College he was able to marry Janet Mitchell (22 July 1789 - 24 April 1879).
- No more worthily-won distinction did his Alma Mater ever confer than when it made him LL.D. Few men knew so much, and fewer still made a better use of what they had than Dr Cruickshank.
- The trust was further augmented on Anne Cruickshank's death to support several other University institutions including a lectureship in Astronomy, the Science Library and a prize in the Faculty of Law.
- Cruickshank became involved with a Scottish trigonometrical survey and in particular with the Belhelvie baseline.
- Another visitor to the measuring site was John Cruickshank, a former pupil of Copland who was later to occupy Copland's chair of mathematics at Marischal College.
- In a short biography of Cruickshank there is an account of Colby's work at Belhelvie as observed by Cruickshank.
- It would appear that the matter was not attended to immediately but was taken up again by John Cruickshank in 1820.
- From 1848 the first three books of Euclid and elementary algebra became a prerequisite for the first mathematical class, enabling Cruickshank to introduce Leibniz' differential and integral calculus, which had replaced fluxions, in his second class.
- Cruickshank corresponded with John Herschel and letters of 1843 and 1847 are extant.
- James Clerk Maxwell was appointed as Professor of Natural Philosophy at Marischal College in 1856 and he and Cruickshank were colleagues for four years.
- Cruickshank was 73, and the senior Professor of Mathematics, but he chose to retire at this time.

Born 5 July 1787, Milltown of Rothiemay, Moray, Scotland. Died 16 November 1875, Aberdeen, Scotland.

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Origin Scotland

**Oâ€™Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive