In 1771, he was employed by baron Mure of Caldwell, to accompany his two sons to France, and to superintend their education at an academy in Paris. The baron, who was at that time one of the most influential men in Scotland, and who lived much in the literary circle of Edinburgh, obtained from his friend David Hume, letters of introduction to several of the French philosophers of that day; by means of which Mr Jardine had the advantage of being acquainted with Helvetius and with D’Alembert, who were then in the zenith of their fame, and whose manners he used to describe as presenting a striking contrast,-- Helvetius having all the style and appearance of a French nobleman of the first fashion, while D’Alembert preserved a primitive simplicity of dress and manner, at that time quite unusual in Paris. During his residence there, he lived a good deal in the society of Dr Gemm, the uncle of Mr Huskisson, who was then settled as a physician in Paris, and noted not only for his eminence in his profession, but for his talents as a philosopher. Dr Gemm was an ardent friend to liberty, and at that time did not scruple to anticipate, to those with whom he was intimate, the fall of the French monarchy as an event at no great distance.

Soon after his return from France, in July, 1773, a vacancy occurred in the humanity chair of Glasgow, by the death of Mr Muirhead; for which a very keen competition arose between him and Mr Richardson, the result of which was doubtful until the very morning of the election, when, notwithstanding every exertion made in behalf of Mr Jardine, by lord Frederic Campbell, the lord rector, Mr Richardson carried the election by a majority of one vote. Upon this occasion, Mr Clow, the professor of logic, who had always befriended Mr Jardine, though, from a prior engagement, he, on this occasion, felt himself obliged to support the other candidate, told him not to be discouraged, for that there might ere long be an opportunity of his being admitted into their society. The expectations which Mr Clow thus kindly threw out, he very soon realized, for, towards the end of the following session, he intimated to the college, that, from his advanced age, he required to be relieved from the labour of teaching, and expressed a wish that Mr Jardine might be associated with him in the professorship. About this time, too, Dr Moor, professor of Greek, gave in his resignation; and in June, 1774, upon the same day, the faculty of Glasgow college elected Mr Young to the Greek chair, and appointed the subject of this memoir assistant and successor to Mr Clow.

By this arrangement, the charge of the three junior classes of Glasgow college came, at the same time, to devolve upon three men in the vigour of life, who all entered most zealously into the business of their respective departments, in which they soon introduced very material improvements:—in particular, they contrived to infuse a spirit of emulation among their pupils by the institution of prizes publicly distributed at the end of each session, to those who had distinguished themselves during the course—an institution which was gradually extended to other classes at Glasgow, and which has now been generally introduced into the other universities. These prizes have been increased during recent years, by the munificence of several of the Lords Rectors, and the generosity of public-spirited individuals. There are prizes bearing the names of James Watt, Lord Jeffrey, Mr James Ewing, the Marquis of Breadalbane, &c., arising from large sums of money permanently invested for that purpose.

The business of the logic class had hitherto consisted in an explanation of the Dialectics of Aristotle, followed up, towards the end of the course, by an exposition of the most abstruse doctrines of metaphysics and ontology, embracing the general attributes of being, existence, essence, unity, necessity, &c, and other similar abstract conceptions of pure intellect. For the first year or two, the new professor followed the same track; but he soon discovered, from the examination of his students, that by far the greater number of them comprehended very little of the doctrines explained; that a few only of superior abilities could give any account of them at all, and that the most of the young men remembered only a few peculiar phrases or technical expressions which they delivered by rote, unaccompanied by any distinct notion of their meaning. Besides, even when these abstract doctrines were understood, intelligent persons who sent their sons to the logic class, could not fail to observe, that the subjects to which their attention was directed had no relation to any profession or employment whatever, and that little could be derived from prelections on such topics, which was likely either to adorn conversation, or to qualify the student for the concerns of active life. Mr Jardine soon perceived, therefore, the necessity of a thorough and radical change on the subjects of his lectures, and after a simple analysis of the different powers of the understanding, with the means of their improvement, accompanied with a short account of Aristotle’s logic, he devoted by far the greater part of the course to the original progress of language; the principles of general grammar; the elements of taste and criticism; and to the rules of composition, with a view to the promotion of a correct style, illustrated by examples. His course of lectures was, accordingly, entirely new-modelled, and he soon found that a great proportion of the students entered with awakened interest upon the consideration of these subjects, instead of the listless inattention which had been bestowed on the abstract doctrines of metaphysics.

But the greatest improvement which he introduced into the mode of conducting the business of the class, was a regular system of examinations and exercises. He was of opinion with Dr Barrow, "that communication of truth is only one half of the business of education, and is not even the most important half. The most important part is the habit of employing, to some good purpose, the acquisitions of memory by the exercise of the understanding; and till this be acquired, the acquisition will not be found of much use." The mere delivery of a lecture, especially to very young persons, he held of very little advantage, unless they were placed in the situation of those who were bound to give an account of it; and the exposition of the rules of composition to be of little avail, unless accompanied by the application of those rules by the student himself. Accordingly, at a separate hour in the forenoon, the students were examined each day on the lecture of the morning, and written essays were required from time to time on subjects more or less connected with those embraced in the lectures. These were regularly criticised by the professor in the presence of the class; and after the principles of criticism had been explained, they were, towards the end of the session, distributed among the students themselves, who were required to subjoin a written criticism upon each other’s performances, under the superintendence of the professor; and prizes were bestowed at the end of the session, according to the determination of the students, to those who excelled in these daily examinations and exercises. This system of practical instruction is explained in all its details in a work published by Mr Jardine before he relinquished the charge of the logic class, entitled "Outlines of Philosophical Education," in which is to be found a full exposition of a system of academical discipline, which was pursued in the logic class of Glasgow, during the period of fifty years it was under his direction, and which was found by experience to be attended with the most beneficial effects.

The details of this system were, of course, attended with no small additional labour to the professor; for, besides two and occasionally three hours each day of public teaching, he had every evening to examine and correct the essays of the students, which were in such numbers as to occupy a large portion of his time. He was reconciled, however, to this tedious and labourius occupation by a thorough conviction of its great practical utility, which each year’s additional experience tended more and more to confirm. He had the satisfaction, too, of knowing that his labours were not without success, both from his students themselves, many of whom did not hesitate to ascribe their advancement in after-life to the active and industrious habits acquired in the logic class, and also from the opinion of the public at large, which was very clearly evinced by the progressive increase of the number of students; the average of which, when he entered upon the office, in the public class was about fifty, but which increased to nearly two hundred. This was, no doubt, partly owing to general causes, applicable to the times, but to a certain extent it was assuredly to be attributed to the great estimation in which this class was held by the public at large. Few teachers have ever enjoyed so large a portion of the respect and affection of their pupils. This was owing not a little to the warm interest which they could not fail to perceive he took in their progress,—to his strict impartiality, which admitted of no preference or distinction of any sort except that of talents and industry,—and to a kindly, affectionate, and almost paternal regard, which marked the whole of his demeanour to his students—who, dispersed, as they afterwards came to be, into all quarters of the globe, have very generally concurred in expressions of cordial esteem to their old preceptor. With such a hold upon the regard and affection of his class, he scarcely ever required to have recourse to the ordinary means of enforcing academical discipline.

From 1774, when he first entered upon his office, till 1824, when he gave up teaching, the business was systematically carried on in the way here described, with such improvements from time to time as were suggested by his experience; and he possessed such an excellent constitution, aided by a temper remarkably cheerful, that during the whole fifty years he was scarcely a single day absent from his class on account of indisposition. His predecessor, Mr Clow, survived till 1788, having the year before his death resigned to his successor the whole privileges of the office, with his seat in the faculty; and, notwithstanding the very laborious duties which he had imposed on himself by his mode of teaching, he still contrived to devote a portion of his time to the extrication of the patrimonial affairs of the college, and the arrangement of their accounts, which his business habits enabled him to undertake without much difficulty, and which, chiefly by his exertions, were brought from a state of comparative confusion into a very satisfactory arrangement. In 1792, likewise, when the royal infirmary was erected at Glasgow, he bestowed very great labour in promoting the undertaking, and for more than twenty years afterwards officiated as secretary, taking on himself the chief management of the affairs of the institution, from which he only retired a short time before his death, when he received the thanks of the managers for the unwearied attention he had bestowed on their business for nearly thirty years.

The private life of Mr Jardine did not present any great variety of incident. During the session he lived in college in terms of great friendship with several of his colleagues, particularly with the late professors Millar and Young, whose views in college affairs generally coincided with his own; and in summer he resided at a small property which he purchased in the neighbourhood of Hamilton, which he took great delight in adorning, and entered with much relish upon the employments of a country life, which formed an excellent relaxation after his winter labours. His residence in that quarter naturally occasioned a connexion with the presbytery of Hamilton, who, for upwards of thirty years, returned him as their representative to the General Assembly, which he regularly attended, taking a considerable share in the business, and generally coinciding in opinion with the late Sir Henry Moncrieff Wellwood, with whom he lived for a great many years in habits of the most unreserved friendship. One of the last public appearances which he made was in May, 1825, upon the question of pluralities, to which he had, on all occasions, been a determined adversary; when he opened the second day’s debate by a forcible speech on the impolicy of uniting professorships with church livings; which, considering his great age, was viewed at the time as a very remarkable effort, and was listened to profound attention.

In 1824, after having taught for fully half a century, he thought himself fairly entitled to retire from his labours. Those who attended the class during that last session did not perceive any abatement either of his zeal or energy; and during that winter he was not absent from his class a single hour. But he foresaw that the time could not be far distant when these exertions must cease, and he preferred retiring before he was actually compelled to do so by the infirmities of age. At the end of that session, he accordingly requested his colleagues to select a person to fill his place; declaring that he left the arrangement entirely to them, and that he would not interfere either directly or indirectly in the appointment, farther than by expressing an earnest wish that they might select one who would take a zealous interest in the prosperity of the class, and would continue the same system of active employment on the part of the students which had been found to be attended with so much benefit. Their choice fell upon the Rev. Robert Buchanan, minister of Peebles, who had himself carried off the first honour at this class, whose literary attainments are of a high order, and who zealously continues to follow out the same system of daily examinations and regular exercises, which was introduced by his predecessor.

Upon the occasion of his retirement from public teaching, a number of those who had been his pupils determined to show their respect by giving him a public dinner in the town hall of Glasgow, which was attended by upwards of two hundred gentlemen, many of whom came from a great distance to evince their respect for their venerable instructor. Mr Mure of Caldwell, his earliest pupil, was in the chair, and the present Marquis of Breadalbane, who had been peculiarly under his charge at Glasgow college, and to whom he was very much attached, came from a great distance to officiate as croupier.

Mr Jardine survived about three years after his retirement from public duties; during which time he resided as usual during winter in college, and continued to take an active interest in the affairs of the society. While attending the General Assembly in May, 1826, he was seized with a bilious attack -- almost the first illness he ever experienced—from which he never completely recovered, and he sank under the infirmities of age on the 27th of January, 1827, having just completed his 85th year; contemplating his dissolution with the composure of a Christian, and expressing his gratitude to the author of his being for the many blessings which had fallen to his lot; of which he did not consider as the least the numerous marks of esteem and regard evinced by his old pupils, with whom he was ever delighted to renew a kindly intercourse. His death was deeply regretted by the society of which he had been so long a member, and by the inhabitants of Glasgow, where he was very generally respected and esteemed.