Sir John threw his personal energy into every work in which he engaged, rousing the inert, stimulating the idle, encouraging the hopeful, and working with all. When a French invasion was threatened, he offered to Mr. Pitt to raise a regiment on his own estate, and he was as good as his word. He went down to the north, and raised a battalion of 600 men, afterwards increased to 1000; and it was admitted to be one of the finest volunteer regiments ever raised, inspired throughout by his own noble and patriotic spirit. While commanding officer of the camp at Aberdeen he held the offices of a Director of the Bank of Scotland, Chairman of the British Wool Society, Provost of Wick, Director of the British Fishery Society, Commissioner for issuing Exchequer Bills, Member of Parliament for Caithness, and President of the Board of Agriculture. Amidst all this multifarious and self-imposed work, he even found time to write books, enough of themselves to establish a reputation. When Mr. Rush, the American Ambassador, arrived in England, he relates that he inquired of Mr. Coke of Holkham, what was the best work on Agriculture, and was referred to Sir John Sinclair’s; and when he further asked of Mr. Vansittart, Chancellor of the Exchequer, what was the best work on British Finance, he was again referred to a work by Sir John Sinclair, his ‘History of the Public Revenue.’ But the great monument of his indefatigable industry, a work that would have appalled other men, but only served to rouse and sustain his energy, was his ‘Statistical Account of Scotland,’ in twenty-one volumes, one of the most valuable practical works ever published in any age or country. Amid a host of other pursuits it occupied him nearly eight years of hard labour, during which he received, and attended to, upwards of 20,000 letters on the subject. It was a thoroughly patriotic undertaking, from which he derived no personal advantage whatever, beyond the honour of having completed it. The whole of the profits were assigned by him to the Society for the Sons of the Clergy in Scotland. The publication of the book led to great public improvements; it was followed by the immediate abolition of several oppressive feudal rights, to which it called attention; the salaries of schoolmasters and clergymen in many parishes were increased; and an increased stimulus was given to agriculture throughout Scotland. Sir John then publicly offered to undertake the much greater labour of collecting and publishing a similar Statistical Account of England; but unhappily the then Archbishop of Canterbury refused to sanction it, lest it should interfere with the tithes of the clergy, and the idea was abandoned.