furnished an instrument exhibiting many improvements, and capable of delighting the most fastidious performers. And all this time his daily devotion to his business was most exemplary, and quite uninterrupted by his reading or speculations, which were pursued in hours not taken up with the labors of his craft. The principle upon which he then acted in this respect guided him throughout life. Before he reached the age of twenty-four, Watt’s attention had been attracted to the employment of steam as a mechanical agent. His friend, Mr. Robison――afterward Professor at Glasgow and Edinburgh――had suggested its application to wheeled carriages, and they made experiments together. Watt doubtless thought much, and submitted the question to close, earnest, and vigilant study. But it was not till 1763 that his abilities were practically applied to the discovery, which has associated his name inseparably with the progress of the world. At that period the model of an engine was sent to him to be repaired by the Professor of the Natural Philosophy class; and on his examining it with care and attention, all the impressions which he had conceived as to the imperfections of the atmospheric machine were at once renewed in his mind. He therefore devoted himself to its improvement with diligence and determination. He soon perceived that the rapidity with which water evaporates depends simply on the degree of heat that is imbibed, and that the latter circumstance is in proportion to the vessel’s surface containing the water. He likewise arrived by experiment at a knowledge as to the coals requisite for the evaporation of any given quantity of water, the heat at which it boils under various pressures, and several other points never before ascertained with accuracy. Bringing his genius to bear on the matter, he proceeded to attempt remedies for the two chief defects of Newcomen’s engine――the necessity of cooling the cylinder before each stroke of the piston by the injection of water, and the non-employment of the engine as a moving power of the expansive force of the steam. Having overcome the first defects by a process which saved three fourths of the fuel required to feed the engine, and at the same time added considerably to its power, Watt was gradually conducted to an improvement which effectually removed the second imperfection; and thus he effected the fundamental amendments in the engine, that, as has been remarked, it appears a thing almost endowed with intelligence.