which were intended for the passage across the isthmus of Panama by the Nicaragua route.
5. Lake Steamers.—Propellers.—A marine engine establishment at Buffalo was principally occupied in making engines for screw steamers intended for lake and river navigation. The propellers of those intended to run in shallow waters are made with four, and sometimes six blades, each, and revolve with rather less than half their diameter immersed in the water. The blades are made of wrought iron, and bolted on
to a cast-iron boss, fitted on the propeller shaft, so that a blade broken or damaged by coming in contact with "snags," or other obstructions, may be easily replaced. Some of the dimensions of machinery in a lake boat, used for carrying cargo, are as follows:—The propeller is 16 feet in diameter, with a pitch of 17 feet 3 inches, making 60 revolutions per minute; the cylinders are 36 inches in diameter, with a 10 feet stroke, and the speed attained averages about eleven miles per hour. The vessel has an upper deck for the accommodation of about 60 passengers. Small high-pressure steam engines for flour mills, agricultural implements, and other machinery, are made in the same establishment.
6. Caloric Engines.—Ericsson's caloric en-
