Camus gave lectures on mathematics in Paris when he was twelve years old. At an early age he had attained the highest academic honors in his own and foreign countries, and had become examiner of engines and professor in the Royal Academy of Architecture in Paris. He published a “Course of Mathematics,” in the second volume of which were two books, or sections, devoted to the consideration of the teeth of wheels, by far the fullest and clearest treatment of this subject then published. These were translated separately, the first English edition appearing in London in 1806, and the second in 1837.[61] In these the theory of spur-, bevel-, and pin-gearing is fully developed for epicycloidal teeth. In the edition of 1837, there is an appendix by John Hawkins, the translator, which is of unusual interest. He gives the result of an inquiry which he made in regard to the English gear practice at that time.[62] As the edition is long since out of print and to be found only in the larger libraries, we give his findings rather fully. His inquiries were addressed to the principal manufacturers of machinery in which gearing was used, and included, among others, Maudslay & Field, Rennie, Bramah, Clement, and Sharp, Roberts & Company. To quote Hawkins: [61] “A Treatise on the Teeth of Wheels.” Translated from the French of M. Camus by John Isaac Hawkins, C.E. London, 1837. [62] _Ibid._, p. 175. A painful task now presents itself, which the editor would gladly avoid, if he could do so without a dereliction of duty; namely, to declare that there is a lamentable deficiency of the knowledge of principles, and of correct practice, in a majority of those most respectable houses in forming the teeth of their wheel-work. Some of the engineers and millwrights said that they followed Camus, and formed their teeth from the epicycloid derived from the _diameter_ of the _opposite wheel_.... One said, “We have no method but the rule of thumb;” another, “We thumb out the figure;” by both which expressions may be understood that they left their workmen to take their own course. Some set one point of a pair of compasses in the center of a tooth, at the primitive circle (pitch-circle), and with the other point describe a segment of a circle for the off side of the next tooth.... Others set the point of the compasses at different distances from the center of the tooth, nearer or farther off; also within or without the line of centers, each according to some inexplicable notion received from his grandfather or picked up by chance. It is said inexplicable, because no tooth bounded at the sides by segments of circles can work together without such friction as will cause an unnecessary wearing away.