"My first essay at making a steam engine was when I was fifteen. I then made a real working; steam-engine, 1 3/4 diameter cylinder, and 8 in. stroke, which not only could act, but really did some useful work; for I made it grind the oil colours which my father required for his painting. Steam engine models, now so common, were exceedingly scarce in those days, and very difficult to be had; and as the demand for them arose, I found it both delightful and profitable to make them; as well as sectional models of steam engines, which I introduced for the purpose of exhibiting the movements of all the parts, both exterior and interior. With the results of the sale of such models I was enabled to pay the price of tickets of admission to the lectures on natural philosophy and chemistry delivered in the University of Edinburgh. About the same time (1826) I was so happy as to be employed by Professor Leslie in making models and portions of apparatus required by him for his lectures and philosophical investigations, and I had also the inestimable good fortune to secure his friendship. His admirably clear manner of communicating a knowledge of the fundamental principles of mechanical science rendered my intercourse with him of the utmost importance to myself. A hearty, cheerful, earnest desire to toil in his service, caused him to take pleasure in instructing me by occasional explanations of what might otherwise have remained obscure."