Even when a boy, Watt found science in his toys. The quadrants lying about his father’s carpenter’s shop led him to the study of optics and astronomy; his ill health induced him to pry into the secrets of physiology; and his solitary walks through the country attracted him to the study of botany and history. While carrying on the business of a mathematical-instrument maker, he received an order to build an organ; and, though without an ear for music, he undertook the study of harmonics, and successfully constructed the instrument. And, in like manner, when the little model of Newcomen’s steam-engine, belonging to the University of Glasgow, was placed in his hands to repair, he forthwith set himself to learn all that was then known about heat, evaporation, and condensation,—at the same time plodding his way in mechanics and the science of construction,—the results of which he at length embodied in his condensing steam-engine. For ten years he went on contriving and inventing—with little hope to cheer him, and with few friends to encourage him. He went on, meanwhile, earning bread for his family by making and selling quadrants, making and mending fiddles, flutes, and musical instruments; measuring mason-work, surveying roads, superintending the construction of canals, or doing anything that turned up, and offered a prospect of honest gain. At length, Watt found a fit partner in another eminent leader of industry—Matthew Boulton, of Birmingham; a skilful, energetic, and far-seeing man, who vigorously undertook the enterprise of introducing the condensing-engine into general use as a working power; and the success of both is now matter of history. {31} Many skilful inventors have from time to time added new power to the steam-engine; and, by numerous modifications, rendered it capable of being applied to nearly all the purposes of manufacture—driving machinery, impelling ships, grinding corn, printing books, stamping money, hammering, planing, and turning iron; in short, of performing every description of mechanical labour where power is required. One of the most useful modifications in the engine was that devised by Trevithick, and eventually perfected by George Stephenson and his son, in the form of the railway locomotive, by which social changes of immense importance have been brought about, of even greater consequence, considered in their results on human progress and civilization, than the condensing-engine of Watt.