In connection mainly with the British India Steam Navigation Company.

This collection consists of the incoming correspondence and letter books of Duncan Mackinnon, a partner in MacKinnon, Mackenzie, and Co, of Calcutta, the firm from which the British India Steam Navigation Compnay developed. This correspondence covers the years 1873, when MacKinnon returned to India after his marriage, to 1881, and the letter books cover a somewhat longer period from 1871 to 1887. This was the period of the Company's heyday, when it rivalled the P and O Line in the size of it's operations, and the collection gives a very good general view of its organisation and day to day running.

As the company was largely a family business, the correspondence also includes a considerable amount of personal information about the people involved. It also includes some of the papers of James MacKinnon, father of Duncan, relating to his career as a seaman, gunner, and latterly second mate, aboard a revenue cruiser based on Stranraer, 1829-51. It also includes some miscellaneous papers relating to shipping in Indian waters, including ship plans, freight charges, and exchange rates.