Two innovations introduced by the Inman line became prominent features of ocean business, and it may be left an open question as to which was the more important. One was the use of the screw-propeller, and the other was the carrying of steerage, or third-class, passengers. Previous to 1850 all steamships built for transatlantic voyages had been side-wheelers, and even as late as 1870 there were steam-vessels that came into the port of New York with the walking-beam, familiar to patrons of modern ferry-boats and river steamers. The principle of the screw-propeller had been known and utilized for many years; but it was not believed that a steamship could cross the ocean in safety unless side-paddles were employed. The first iron transatlantic screw steamship was the City of Glasgow (except the Great Britain, which first arrived in New York on September 10, 1845, making but two transatlantic trips, and therefore not entering as a factor into this trade), built on the Clyde by Tod & McGregor. She made four successful voyages between Glasgow and New York before she was purchased by the corporation that afterward became known as the Inman line. This innovation, although it did not result at first in any marked increase of speed, soon found approbation in the policies of rival companies. [Illustration: A Quiet Flirtation.] The other innovation was equally long in finding acceptance among oceanic steamship companies, but it eventually prevailed, even to the extermination of the clipper ship as a passenger carrier. It may be remarked just here that the introduction of the screw-propeller added to the discomforts of the cabin passengers; for in the first vessels of the Inman line the state-rooms and saloons were retained in the after-part of the ships, where the motion of the sea and the noise of the screw were most apparent. Leaving this matter for the present, it is worth noting that the steady increase in passenger traffic between the two continents led to the organization of many other companies that tried to find a share in the carrying business. The Glasgow & New York Steamship Company was started in 1854 by Tod & McGregor, ship-builders; the service was fortnightly. In 1859 they decided to confine their business to ship-building, and the fleet and good-will were then sold out to the Inman line, who continued the service for a year or two, but finally withdrew the fleet from Glasgow and concentrated their entire business between Liverpool, Queenstown, and New York.