In 1807 Evans was established as “Millwright and Engineer” at the Mars Works at Ninth and Vine Streets. An old description of the plant says that it consisted of an iron foundry, mould-maker’s shop, steam engine manufactory, blacksmith’s shop, and mill-stone manufactory, and a steam engine used for grinding materials for the use of the works, and for turning and boring heavy cast or wrought iron work. The buildings occupy one hundred and eighty-eight feet front and about thirty-five workmen are daily employed. They manufacture all cast or wrought-iron work for machinery for mills, for grinding grain or sawing timber; for forges, rolling and slitting-mills, sugar-mills, apple-mills, bark-mills, &c. Pans of all dimensions used by sugar-boilers, soap-boilers, &c. Screws of all sizes for cotton-presses, tobacco-presses, paper-presses, cast iron gudgeons, and boxes for mills and wagons, carriage-boxes, &c., and all kinds of small wheels and machinery for Cotton and Wool spinning, &c. Mr. Evans also makes steam engines on improved principles, invented and patented by the proprietor, which are more powerful and less complicated, and cheaper than others; requiring less fuel, not more than one-fiftieth part of the coals commonly used. The small one in use at the works is on this improved principle, and it is of great use in facilitating the manufacture of others. The proprietor has erected one of his improved steam engines in the town of Pittsburg, and employed it to drive three pair of large millstones with all the machinery for cleaning the grain, elevating, spreading, and stirring and cooling the meal, gathering and bolting, &c., &c. The power is equal to twenty-four horses and will do as much work as seventy-two horses in twenty-four hours; it would drive five pair of six-feet millstones, and grind five hundred bushels of wheat in twenty-four hours.[203] [203] Freedley: “Philadelphia and its Manufactures,” pp. 54-55. Philadelphia, 1858. Incidentally the last sentence is an admirable illustration of the origin of the term “horse power.” This business was carried on until Evans’ death. It would be interesting to know how far he influenced the design of Mississippi river boat engines which have retained the proportions characteristic of the engines which he first built for that service. Evans’ best-known book, “The Young Millwright and Miller’s Guide,” went through a number of editions and was translated and published abroad. In this he gives his idea of “The True Path to Inventions.” It is well worth quoting, as it explains, in part, his own success as an inventor. Necessity is called the mother of Invention--but upon inquiry we shall find that Reason and Experiment bring them forth.--For almost all inventions have resulted from such steps as the following: