But as regards Physical Science, the progress made during the last hundred years has been very great. Its most recent triumphs have been in connection with the discovery of electric power and electric light. Perhaps the most important invention, however, was that of the working steam engine, made by Watt only about a hundred years ago. The most recent application of this form of energy has been in the propulsion of ships, which has already produced so great an effect upon commerce, navigation, and the spread of population over the world. Equally important has been the influence of the Railway--now the principal means of communication in all civilized countries. This invention has started into full life within our own time. The locomotive engine had for some years been employed in the haulage of coals; but it was not until the opening of the Liverpool and Manchester Railway in 1830, that the importance of the invention came to be acknowledged. The locomotive railway has since been everywhere adopted throughout Europe. In America, Canada, and the Colonies, it has opened up the boundless resources of the soil, bringing the country nearer to the towns, and the towns to the country. It has enhanced the celerity of time, and imparted a new series of conditions to every rank of life. The importance of steam navigation has been still more recently ascertained. When it was first proposed, Sir Joseph Banks, President of the Royal Society, said: "It is a pretty plan, but there is just one point overlooked: that the steam-engine requires a firm basis on which to work." Symington, the practical mechanic, put this theory to the test by his successful experiments, first on Dalswinton Lake, and then on the Forth and Clyde Canal. Fulton and Bell afterwards showed the power of steamboats in navigating the rivers of America and Britain. After various experiments, it was proposed to unite England and America by steam. Dr. Lardner, however, delivered a lecture before the Royal Institution in 1838, "proving" that steamers could never cross the Atlantic, because they could not carry sufficient coal to raise steam enough during the voyage. But this theory was also tested by experience in the same year, when the Sirius, of London, left Cork for New York, and made the passage in nineteen days. Four days after the departure of the Sirius, the Great Western left Bristol for New York, and made the passage in thirteen days five hours.[1] The problem was solved; and great ocean steamers have ever since passed in continuous streams between the shores of England and America. In an age of progress, one invention merely paves the way for another. The first steamers were impelled by means of paddle wheels; but these are now almost entirely superseded by the screw. And this, too, is an invention almost of yesterday. It was only in 1840 that the Archimedes was fitted as a screw yacht.