It was while at Glasgow University, working under such influences and in such an atmosphere of intellectual activity, that the accident of the Newcomen model engine needing repair brought to the mind of Watt the opportunity which, availed of at once, made him famous and gave the world its greatest aid, its most powerful servant.  The observing mind of the great mechanic immediately noted its defects, sought their causes, found their remedy.  He discovered, at once, that the quantity of steam entering the cylinder of the little engine has four times the volume of the cylinder receiving it:  in other words, three-fourths of that steam must be condensed immediately on entrance.  This meant, evidently, that only one-fourth of the steam supplied was utilized, and even then inefficiently, in doing its work.  The reason of this was as easily seen, immediately the fact was revealed.  As Watt himself expressed it, the causes of this loss, causes which would obviously be exaggerated in a small engine, were:  “First, the dissipation of heat by the cylinder itself, which was of brass and both a good conductor and a good radiator.  Secondly, the loss of heat consequent upon the necessity of cooling down the cylinder at every stroke in producing the vacuum.  Thirdly, the loss of power due to the pressure of vapor beneath the piston, which was a consequence of the imperfect method of condensation.”  This much determined, the next step looked toward the confirmation of his conclusions and the remedy of the defects.

To meet the first difficulty he made a cylinder of wood, soaked in oil and baked, a non-conducting and non-radiating material.  Then he was able to determine with some accuracy the quantities of steam and injection water used in the engine; and a comparison with the original cylinder and its operation showed that not only four times the quantity of steam, but also four times the amount of injection water was used as was necessary, assuming wastes checked.  Further scientific research on the part of Watt gave him measures of specific heats of the metals and of wood, the specific volumes of steam at various working pressures, the evaporative efficiency of boilers, the pressures and temperatures of steam in the boiler under specified conditions, the quantities of steam and of water required for the operation of his little condensing engine.

Then came his enunciation of the grand principle of economy in the construction and operation of the steam engine:  “Keep the cylinder as hot as the steam which enters it,” as he expressed it.  This was Watt’s guiding principle, as it has been that of all his successors in the improvement of the economic performance of the steam engine and of all other heat engines.  The great source of waste is the dispersion of heat, uselessly, which should be applied to the production of work by its transformation, thermodynamically, into the latter form of energy.  The second form of waste is that of power thus produced in the unprofitable work of