. . .ave invented the separate condenser and ranked as a great inventor, but the spirit of enquiry was in possession of him, and he had to find out all he could about the nature of steam.

His first discovery was that of latent heat. When communicating this to Professor Black he found that his friend had anticipated him, and had been teaching it in lectures to his students for some years past. His next step was the discovery of the total heat of steam, and that this remains practically constant at all pressures. Black's fame rests upon his theory of latent heat; Watt's fame as the discoverer of the total heat of steam should be equally great, and would be no doubt had his rôle of inventor not overshadowed all his work.

This part of Watt's work has been so little known that it is almost imperative to-day to give some idea of it to the general reader. Suppose you take a flask, such as olive oil is often sold in, and fill with cold water. Set it over a li. . . Read More