John Lang Cassels, M.D., LL.D., was born in Stirlingshire, Scotland, and in 1827, while quite a young man, came to this country. Soon after, he studied medicine with Prof. John Delamater, in Fairfield, New York, and graduated in 1834, in the College of Physicians and Surgeons located at Fairfield, N. Y. He was Demonstrator of Anatomy in that school three years, two years during his pupilage and one after his graduation. He opened an office for the practice of medicine in Earlville, New York, in the spring of 1835, and in the fall of the same year received and accepted the appointment of Professor of Chemistry in Willoughby University, Ohio, which connection he retained until the fall of 1843, when he and his associates opened and established the Cleveland Medical College, in which he still occupies the chair of Chemistry.

In 1837, he received the appointment of First Assistant Geologist of the New York State Geological Survey, which he occupied for several seasons, performing field labor in the summer and lecturing on chemistry in Willoughby Medical College during the winter. His connection with the New York survey gave him an excellent opportunity to become an expert practical geologist; his location being on the Hudson river district, offered him a fine field of action, as it is really the key to the geology and mineralogy of the State.

In the winter of 1839, he gave a course of demonstrated lectures on chemistry before the Young Men's Library Association in Cleveland, the first public lectures on science ever given in the city. The following winter the citizens of Cleveland invited him to lecture again on the same subject, and he complied. The city at that time contained mostly young people--only two gray-headed men attended the Stone Church.

In 1815, he spent most of the season in visiting and collecting specimens of mineral in the lead region of Wisconsin, Illinois, Iowa and Missouri, thus becoming familiar with the geology of their rich mineral region.

In 1846, he spent the whole season in exploring the Lake Superior country, coasting the south shore in a bark canoe, having for his traveling companions two Indians and a half-breed voyager. At this date there were no steamers on Lake Superior, and but a very few small sailing craft. It was during this time that he took squatter possession of a mile square of the iron region of that country, for the benefit of the Cleveland Iron Company. He was the first white man that had visited this region, now so famous for its ferruginous wealth. Near the close of the season he spent a short time geologizing Isle Royale, and returned to Saut St. Marie on the steamer Julia Palmer, which had, during the summer, been hauled over the passage of Saut St. Marie. During the winter following, at the request of a number of Clevelanders, he gave a public lecture on the Lake Superior region; at the close of which he said he would venture a prophecy: "Such was the character of the climate, scenery, etc., of Lake Superior that the time was not far distant when it would become as great a resort for invalids and pleasure-seekers as Saratoga and Newport now are." Also, that there is iron enough in the iron district sufficient to furnish a double track of the much talked of Whitney's railroad. These statements were then received with a stormy manifestation of incredulity.

In 1859, the Jefferson College of Mississippi conferred the Degree of LL.D. on Dr. Cassels.

In 1861, he was elected a corresponding member of the Imperial Geological Institution of Berlin, Prussia.

For the last ten years, in addition to the duties of his chair in the Cleveland Medical College, he has regularly filled the chair of chemistry and natural history in the Western Reserve College at Hudson. During the past twenty years he has given several courses of popular experimental lectures in his favorite branches of chemistry and geology in a number of our neighboring towns, Akron, Canton, &c. He is also the regular lecturer in these branches in the Female Seminary in Painesville.

Perhaps few men have been as extensively engaged in texicological examinations during the past twenty years as Dr. Cassels. Many of these have been of great interest, both in a social and moral point of view. In all such cases he is regarded with great confidence, both on account of his scientific skill and his high sense of moral integrity.

As an analytical chemist he has few superiors, and is much of his spare time engaged in the analysis of waters, ores, coal, limestone, &c. In 1866, he analyzed the water of Cleveland which is brought from Lake Erie and distributed through the city. He analyzed this water taken from different parts of the city and from the point where it entered the pipes to be forced into the reservoir; also from a point in the lake three thousand four hundred and fifty feet from the shore, where he advised that the inlet pipe ought to be located. All these analyses are embraced in his report to the Trustees of the city water works; in which also are many valuable suggestions respecting supply pipes and the character of the water for steam purposes.