The _Pacific_ was provided with two engines, each supported upon a large and solid bed-plate 32 feet long, and 9 feet broad, which was fastened to the keelson and ship’s bottom by bolts of large dimensions previously fixed in the wood; it was a single casting having a channel below in which there was a foot valve, and above it the cylinder bottom, the air-pump seat, and also a great part of the condenser, through which the side-lever shaft passed: it also had upon it sockets for the different pieces of the frames. On the cylinder bottom, at the extremity of the bed-plate, the cylinder itself was bolted, the largest at that time ever cast: its diameter being 96 inches, calculated for a stroke of 9 feet, and length, flange to flange, 10 feet 6 inches. The lower steam-opening being cast with the bed-plate, the upper one alone belonged to the cylinder. The steam exhaust valves were on the plan generally adopted in the United States and arranged with Stevens’s “cut off,” so as to let the steam expand one-half its volume. The steam passed from the boiler to the upper steam-opening by a large pipe 2 feet in diameter and about twenty feet long, and after doing its duty in the cylinder, escaped by the middle of the exhaust side pipe, and reached the condenser, which was not more than 1 foot distant, through a pipe of the same section. The condenser and the reservoir were formed by a single casting inside which was a partition between them of the same casting. This piece was ornamented in the same style as the steam-chest, and supported a beautiful turret used as an air reservoir, which rather resembled an old castle of the Middle Ages than a steam engine of the nineteenth century, and gave an imposing appearance to the whole structure. The steam, arriving in the condenser between two horizontal iron plates, which were pierced over the whole surface, causing the condensing water to fall in small streams through them, so as to be soon condensed; then passing through the foot valve under the condenser, it reached the air-pump, which was situated on the other side of the condenser. The condenser was so much elevated that the steam required to make a vertical descent of 11 feet, mixed with cold water, before reaching the channel way, thereby furnishing the means of quick condensation with a condenser of comparatively small size. All the pieces of the engine, cylinders, levers, connecting rods, &c., were calculated upon the best rules then known,[200] and the straps, keys, gibs, ribs, mouldings, &c., were so disposed as to produce the maximum of strength and security against accidents: but the pre-eminent success was in the design of the frame. [Sidenote: Frame sustaining engines and dead weight.]