Born in the Manse of Kiltarlity, one of the large Inverness-shire parishes, on July 5th, 1779; his father and his grandfather had been ministers of the parish. He was apprenticed to a medical man at Inverness and afterwards became a student at St George's Hospital, where he served the office of House Surgeon and Assistant to Sir Everard Home and became a friend of his contemporaries, Sir Benjamin Brodie and Sir Charles Clarke. He practised for some time in London until Sir Everard Home in 1805 gave him a nomination in the service of the HEIC. He entered the Bengal Army as Assistant Surgeon on Feb 2nd, 1807, his appointment being delayed as he was acting as Private Surgeon to the Duke of Portland. He was detailed as Assistant Surgeon to the Calcutta General Hospital as soon as he arrived in India, and spent nearly all his working life in connection with the institution. On Jan 8th, 1820, he was promoted Surgeon, and in 1827 Superintending Surgeon, in the service of the HEIC, but he resigned this rank and reverted to his appointment as Residency Surgeon at Calcutta, and held office until a few days before his death. Nicolson soon obtained a very large practice in Calcutta, and it is said that horses were in harness day and night whilst a coachman sat on the box of his carriage ready for any urgent summons; yet in spite of this he was not ostentatious and never grew rich, for he gave of his best in the matter of advice to rich and poor alike. When John Macdonald came to India in 1838 Nicolson was one of the first to enrol himself and his family in the New Scottish Free Church in India. His last years were darkened by misfortune: his eldest son was killed in the Battle of Ferozshakar; a few months later his wife died after a long illness; and he himself became paralysed in 1847. On resigning his post of Surgeon to the Hospital at Calcutta he received a letter from the Marquis of Dalhousie, the Governor-General, dated April 25th, 1855, and another from the President of the Council of India, congratulating and thanking him for all the good work he had done during the nearly fifty years he had held office. He died at Calcutta on August 8th, 1855, after a short illness.