At Roorkee were the extensive engineering workshops connected with the canal.  Yule soon became so accustomed to the din as to be undisturbed by the noise, but the unpunctuality and carelessness of the native workmen sorely tried his patience, of which Nature had endowed him with but a small reserve.  Vexed with himself for letting temper so often get the better of him, Yule’s conscientious mind devised a characteristic remedy.  Each time that he lost his temper, he transferred a fine of two rupees (then about five shillings) from his right to his left pocket.  When about to leave Roorkee, he devoted this accumulation of self-imposed fines to the erection of a sun-dial, to teach the natives the value of time.  The late Sir James Caird, who told this legend of Roorkee as he heard it there in 1880, used to add, with a humorous twinkle of his kindly eyes, “It was a very handsome dial."[33]

From September, 1845, to March, 1847, Yule was much occupied intermittently, in addition to his professional work, by service on a Committee appointed by Government “to investigate the causes of the unhealthiness which has existed at Kurnal, and other portions of the country along the line of the Delhi Canal,” and further, to report “whether an injurious effect on the health of the people of the Doab is, or is not, likely to be produced by the contemplated Ganges Canal.”

“A very elaborate investigation was made by the Committee, directed principally to ascertaining what relation subsisted between certain physical conditions of the different districts, and the liability of their inhabitants to miasmatic fevers.”  The principal conclusion of the Committee was, “that in the extensive epidemic of 1843, when Kurnaul suffered so seriously ... the greater part of the evils observed had not been the necessary and unavoidable results of canal irrigation, but were due to interference with the natural drainage of the country, to the saturation of stiff and retentive soils, and to natural disadvantages of site, enhanced by excess of moisture.  As regarded the Ganges Canal, they were of opinion that, with due attention to drainage, improvement rather than injury to the general health might be expected to follow the introduction of canal irrigation."[34] In an unpublished note written about 1889, Yule records his ultimate opinion as follows:  “At this day, and after the large experience afforded by the Ganges Canal, I feel sure that a verdict so favourable to the sanitary results of canal irrigation would not be given.”  Still the fact remains that the Ganges Canal has been the source of unspeakable blessings to an immense population.

The Second Sikh War saw Yule again with the army in the field, and on 13th Jan. 1849, he was present at the dismal ‘Victory’ of Chillianwallah, of which his most vivid recollection seemed to be the sudden apparition of Henry Lawrence, fresh from London, but still clad in the legendary Afghan cloak.