making my flywheels for the sectional models of steam-engines I had a rather neat and handy way of constructing them. The boss of the wheel of brass was nicely bored; the arm-holes were carefully drilled and taped, so as to allow the arms which I had turned to be screwed in and appear like neat columns of round wrought iron or steel screwed into the boss of the flywheel.

In return for the great kindness of George Douglass in allowing me to have the use of his foundry, I resolved to present him with a specimen of my handiwork. I desired to try my powers in making a more powerful steam-engine than I had as yet attempted to construct, in order to drive the large turning-lathe and the other tools and machinery of his small foundry. I accordingly set to work and constructed a direct-acting, high-pressure steam-engine, with a cylinder four inches in diameter. I use the term direct acting, because I dispensed with the beam and parallel motion, which was generally considered the correct mode of transferring the action of the piston to the crank.

The result of my labours was a very efficient steam-engine, which set all the lathes and mechanical tools in brisk activity of movement. It had such an enlivening effect upon the workmen that George Douglass afterwards told me that the busy hum of the wheels, and the active, smooth, rhythmic sound of the merry little engine had, through some sympathetic agency, so quickened the stroke of every hammer, chisel, and file in his workmen's hands, that it nearly doubled the output of work for the same wages!

The sympathy of activity acting upon the workmen's hands cannot be better illustrated than by a story told me by my father. A master tailor in a country town employed a number of workmen. They had been to see some tragic melodrama performed by some players in a booth at the fair. A very slow, doleful, but catching air was played, which so laid hold of the tailors' fancy that for some time after they were found slowly whistling or humming the doleful ditty, the movement of their needles keeping time to it; the result was that the clothing that should have been sent home on Saturday was not finished until the Wednesday following. The music had done it! The master tailor, being something of a philosopher, sent his men to the play again; but he arranged that they should be treated with lively merry airs. The result was that the lively airs displaced the doleful ditty; and the tailors' needles again reverted to even more than their accustomed quickness.

However true the story may be, it touches an important principle in regard to the stimulation of activity by the rapid movements or sounds of machinery, which influence every workman within their sight or hearing. We all know the influence of a quick merry air, played by fife and drum, upon the step and marching of a regiment of soldiers. It is the same with the quick movements of a steam-engine upon the activity of workmen.

I may add that my worthy friend, George Douglass, derived other advantages from the construction of my steam-engine. Being of an enterprising disposition he added another iron foundry to his smaller shops; he obtained many good engineering tools, and in course of time he began to make steam-engines for agricultural purposes. These were used in lieu of horse power for thrashing corn, and performing several operations that used to be done by hand labour in the farmyards. Orders came in rapidly, and before long the chimneys of Douglass's steam-engines were as familiar in the country round Edinburgh as corn stacks. All the large farms, especially in Midlothian and East Lothian, were supplied with his steam-engines. The business of George Douglass became very large; and in course of time he was enabled to retire with a considerable fortune.

In addition to the steam-engine which I presented to Douglass, I received an order to make another from a manufacturer of braiding. His machines had before been driven by hand labour; but as his business extended, the manufacturer employed me to furnish him with all engine of two-horse power, which was duly constructed and set to work, and gave him the highest satisfaction.

James Nasmyth's Expansometer, 1826.

I may here mention that one of my earliest attempts at original contrivance was an Expansometer -- an instrument for measuring in bulk all metals and solid substances. The object to be experimented on