The _Great Eastern_ was, in accordance with Brunel’s idea, propelled by both paddle-wheels and a screw. An illustration is here given of a model of her paddle-engines, which were of the oscillating type. It will be borne in mind that the leading advantages of this type lay in the fact of their comparative lightness in weight, and their economy as regards space. If the reader will just glance at the illustration which faces page 138 of the _Great Eastern’s_ longitudinal section, he will be able to see what little room these engines actually needed. It will be noticed in her paddle-engines that each of two cylinders drove a crank, the cylinders being placed vertically but at an inclined angle. Each paddle-wheel could, if desired, be driven separately. The condensers were of the jet type, and there were two air-pumps, which were driven by a single crank in the middle of the paddle shaft. The paddle-wheels were tremendous, weighing ninety tons each, and measuring fifty-six feet in diameter. But the _Great Eastern_ amply proved how unsuitable the paddle-wheel was for ocean work. Every time the big monster rolled in a bad sea a great strain was put on the machinery; these vast projections, too, offered not merely increased windage and accentuated the ship’s general unwieldiness, but afforded a fine target for the Atlantic waves to smash against. Once the _Great Eastern_, during a gale in the year 1861, suffered pretty badly in this respect, when the paddle-wheels were destroyed. She was afterwards fitted with wheels five feet smaller in diameter, and of greater strength.