IF it be asked what James Watt did during his long, busy, and eventful life to improve ocean navigation, or to adapt the steam engine to the work of propelling ships, I am obliged to reply that I am not aware he personally did anything, or even that he concerned himself much about the matter. He took no active part that we know of in applying or adapting his steam engine to the propulsion of ships. The reason probably was that after his attention was first directed to the subject of the steam engine, or fire engine, in 1759, his whole energy was expended, first in improving the steam engine and making its manufacture commercially successful, and afterwards in executing the orders that came for pumping and other engines that were required for mines and manufactures. In the case of most of the greatest mechanical inventions—Watt's among the number—it has not been the ideas or the inventions hy themselves that have brought success, prospeaty, or even satisfaction to their owners. These results have had to be painfully and slowly evolved out of long and costly practical demon trations and experience of the alleged merits of the invention. James Watt toiled, suffered and endured for more than twenty years after his discovery of separate condensation in 1765, before he could see that his steam engine would ever bring him anything but disappointment, loss, and misery. It is highly characteristic, however, of Watt's fertile and original genius, and significant of what he might have done to develop the marine engine at the commencement of its history, had he taken the matter up, that upon the two principal occasions we know of when he applied his mind to the subject, he made very pregnant suggestions. Thus, when Watt sent drawings of his engines to Soho in 1770 for Mr. Boulton to construct one for experiment, and had been told that it was intended to make an engine to draw canal boats, Watt wrote, “Have you ever considered a spiral oar for that purpose, or are you for two wheels?” and to make his meaning clear he sketched a rough but graphic outline of a screw propeller. This is, perhaps, the earliest suggestion of a screw propeller, except that it was proposed by Daniel Bernoulli, ihe mathematician, in 1752. Again, in 1816, four years after the first Clyde steamboat, the Comet, was built at Port Glasgow, when Mr. Watt was upon his last visit to Greenock, he went to Rothesay and back in a steamboat. At that time the engineer did not reverse his engines, but merely stopped them some time before the vessel reached her mooring-place, and let her gradually slow down. James Watt, then an old man of eighty, tackled the engineer of the boat, and showed him how the engine could be reversed. He tried to explain this with the aid of a foot rule, but not being successful in doing it to the complete satisfaction of the engineer, he is said to have thrown off his overcoat and given a practical demonstration. Although Watt never took up the subject of steam navigation and never made a marine engine, still he was in reality its originator, because he discovered and provided the means by which it could be applied with advantage to the propulsion of ships. Each of his great improvements upon the old engine that worked by atmospheric pressure and condensed its steam in the cylinder—such as the separate condenser, the working by steam pressure as well as by pressure obtained by vacuum, the double action of the steam in the cylinder on both sides of the piston, working the steam expansively, the centrifugal governor for automatically regulating the speed of the engine, and many others—was a direct adaptation for marine purposes.