On the conclusion of the Punjab campaign, Yule, whose health had suffered, took furlough and went home to his wife.  For the next three years they resided chiefly in Scotland, though paying occasional visits to the Continent, and about 1850 Yule bought a house in Edinburgh.  There he wrote “The African Squadron vindicated” (a pamphlet which was afterwards re-published in French), translated Schiller’s Kampf mit dem Drachen into English verse, delivered Lectures on Fortification at the, now long defunct, Scottish Naval and Military Academy, wrote on Tibet for his friend Blackwood’s Magazine, attended the 1850 Edinburgh Meeting of the British Association, wrote his excellent lines, “On the Loss of the Birkenhead,” and commenced his first serious study of Marco Polo (by whose wondrous tale, however, he had already been captivated as a boy in his father’s library—­in Marsden’s edition probably).  But the most noteworthy literary result of these happy years was that really fascinating volume, entitled Fortification for Officers of the Army and Students of Military History, a work that has remained unique of its kind.  This was published by Blackwood in 1851, and seven years later received the honour of (unauthorised) translation into French.  Yule also occupied himself a good deal at this time with the practice of photography, a pursuit to which he never after reverted.

In the spring of 1852, Yule made an interesting little semi-professional tour in company with a brother officer, his accomplished friend, Major R. B. Smith.  Beginning with Kelso, “the only one of the Teviotdale Abbeys which I had not as yet seen,” they made their way leisurely through the north of England, examining with impartial care abbeys and cathedrals, factories, brick-yards, foundries, timber-yards, docks, and railway works.  On this occasion Yule, contrary to his custom, kept a journal, and a few excerpts may be given here, as affording some notion of his casual talk to those who did not know him.

At Berwick-on-Tweed he notes the old ramparts of the town:  “These, erected in Elizabeth’s time, are interesting as being, I believe, the only existing sample in England of the bastioned system of the 16th century....  The outline of the works seems perfect enough, though both earth and stone work are in great disrepair.  The bastions are large with obtuse angles, square orillons, and double flanks originally casemated, and most of them crowned with cavaliers.”  On the way to Durham, “much amused by the discussions of two passengers, one a smooth-spoken, semi-clerical looking person; the other a brusque well-to-do attorney with a Northumbrian burr.  Subject, among others, Protection.  The Attorney all for ’cheap bread’—­ ‘You wouldn’t rob the poor man of his loaf,’ and so forth.  ’You must go with the stgheam, sir, you must go with the stgheam.’  ’I never did, Mr Thompson, and I never will,’ said the other in an oily manner, singularly inconsistent