Richard Cockburn Maclaurin was born at Lindean railway station, Galashiels, Selkirkshire, Scotland, on 5 June 1870, the son of Robert Campbell Maclaurin, the resident stationmaster, previously a clergyman, and his wife, Martha Joan Spence. In 1875 he travelled to New Zealand with his mother to join his father and two older brothers, who had arrived the year before. His father was to become a schoolteacher, and the family lived at Alexandra (Pirongia), Te Awamutu and Hautapu. Maclaurin attended Auckland College and Grammar School and then, having won a university Junior Scholarship, went to Auckland University College. He was regarded as one of the college's most outstanding students.
In 1891 Maclaurin was awarded first-class honours in mathematics and a foundation scholarship to enter St John's College at the University of Cambridge. There he was top equal in the second part of the mathematical tripos, and won the prestigious Smith's Prize for the same subject. He then took up law and, after studying philosophy in Strasburg in 1897, entered Lincoln's Inn with a studentship. In 1898 he won the Yorke Prize for a dissertation on title to realty.
In 1899 Maclaurin returned to New Zealand as the foundation professor of mathematics at the newly founded Victoria College in Wellington. On arrival he was required to teach law as well as mathematics, although the council declined to give him any additional salary. In 1907 he became professor of law, dean of the Faculty of Law and honorary professor of astronomy. He was the first chairman of the college's professorial board.
On 27 December 1904, at Auckland, Maclaurin married Margaret Alice Pairman Young. The Maclaurins were Presbyterians although later, in the United States, they joined the Congregationalist church.
Maclaurin was a brilliant scholar. In 1901 he published On the nature of evidence of title to realty, and in 1904 Cambridge University conferred on him the degree of LLD. In the Proceedings of the Royal Society of London he published papers which led to his book The theory of light: a treatise on physical optics, published in 1908. Personally he was very witty, an amusing raconteur and very popular with his colleagues and students. But he could not be kept in New Zealand, where his college was run on a meagre budget: its annual government grant was a mere £4,000. Besides, in seven years he had only three honours students.
In 1907 Maclaurin accepted an offer from Columbia University in New York of the chair of mathematical physics. Within a year, however, he left Columbia when, at the age of 39, he was offered the post of president of the Massachusetts Institute of Technology. This offer arose because it was known that he had made a deep study of scientific education. He had, however, only a minimal experience of academic administration; and, apart from signing an appeal for building funds in Wellington, he had no experience of fund-raising, which was to be his chief task at MIT.
Maclaurin, however, proved a remarkable success after taking up his position in 1909. The institute was in severe financial difficulties and in danger of being taken over by Harvard University. Maclaurin quickly established a close rapport with several millionaires, including George Eastman of the Eastman Kodak Company. Like Maclaurin, he saw the immense importance of technical education if the United States were to stay in the forefront of science, industry, and, indeed, power. Both men were devotees of efficiency and business methods. Eastman alone was to donate millions of dollars to MIT; other rich men and alumni gave millions more. With these funds Maclaurin established the institute in an impressive and large building on a new site on the Charles River; he also secured valuable endowments to guarantee its future. By a 'sort of irony of fate', Maclaurin wrote, he who had 'so often criticized the educational authorities for acting as if buildings make the institution', now found himself a chief advocate for buildings and sites.
Maclaurin was a slight man and often ill; the stress of his fund-raising activities took its toll. He died suddenly at Cambridge, Massachusetts, on 15 January 1920 at the age of 49. He was survived by his wife and two sons. His New Zealand career, full of promise, was too brief to be of lasting significance; his achievements in Boston showed what New Zealand had lost.