Page:Popular Science Monthly Volume 12.djvu/275

Rh improving the details of mill-work, and with such success as to reduce the cost of attendance one-half, and also to increase the fineness of the flour made.

In 1785 he applied for, but was refused, a patent for a steam carriage.

In 1800 or 1801, Evans, after consulting with Prof. Robert Patterson, of the University of Pennsylvania, and getting his approval of the plans, commenced the construction of a steam-carriage, to be driven by a non-condensing engine.

He soon concluded, however, that it would be a better scheme, pecuniarily, to adapt his engine, which was novel in form and of small first cost, to driving mills; and he accordingly changed his plans, and built an engine of six inches diameter of cylinder and eighteen inches stroke of piston, which he applied with perfect success to driving a plaster mill.

51. This engine (Fig. 27), which he called the "Columbian engine," was of a peculiar form.

The beam is supported at one end by a rocking column; at the other it is attached directly to the piston-rod, while the crank lies beneath the beam, the connecting-rod being attached to the latter at about the middle point.

The head of the piston-rod is compelled to rise and fall in a vertical line by the "Evans parallelogram," a kind of parallel motion very similar to one of those designed by Watt.

52. Subsequently, Evans continued to extend the application of his engine and to perfect its details, and, others following in his track, the non-condensing engine is to-day fulfilling the predictions which he made seventy years ago, when he said:

"I have no doubt that my engine will propel boats against the currents of the Mississippi, and wagons on turnpike-roads, with great profit. . ..

"The time will come when people will travel in stages moved by steam engines, from one city to another, almost as fast as birds can fly—fifteen or twenty miles an hour. A carriage will start from Washington in the morning, the passengers will breakfast at Baltimore, dine at Philadelphia, and sup at New York the same day. . ..

"Engines will drive boats ten or twelve miles an hour, and there will be hundreds of steamers running on the Mississippi, as predicted years ago."

53. In 1804 Oliver Evans completed a flat-bottomed boat (Fig. 28), to be used at the Philadelphia docks, and, mounting it upon wheels, drew it by its own steam-engine to the river-bank. Launching the craft, he propelled it down the river, using its steam-engine to drive its paddle-wheels. Evans's "oructor amphibolis" as he named the machine, was the first road-locomotive that we find described after Cugnot's time. Evans asserted that carriages propelled by steam would soon be in common use; and offered a wager of three hundred