to fit wrist, and accurately fitted into jaws. Cotter one and seven-eighths inch broad at one end, and tapering to three- fourths inch at the other; thickness, one inch; length, two feet six inches; gibs, eighteen inches long, one inch thick, four inches broad at one end, at the other three and five-eighths inches, locking over strap one and one-eighth inches; a deep secured to cotter, and gibe with five-eighths screw to be provided. Main pillow block, cast iron, base five feet six inches long, ten inches broad, three inches thick; for four feet two and one-fourth inches, for nine inches on each, on which fit the guides for cam yokes. Thickness of metal for sides, half circle five-inch radius, supported with a bracket with a hole in each for a bolt one and one-half inches diameter to hold down the cap; height of sides, six inches; thickness of metal, three inches; block in held down with five 1 1/4-inch bolts and nuts; bottom brasses to be not less than one inch thick, well fitted into the block; side brasses for one and one-half inches deep, planed and fitted into their places; flange one and three-fourths inches wide, backed up with a wedge; the length and breadth of brass in the usual way; the end brasses to be fitted into their places, and all bored out together; brasses to be filled with Babbitt metal. At each end of the block and let into the frame timbers is a chock ten inches square, two and one-half inches thick, held down with a 1 1/4-inch bolt and nut; the outer end has a projection the whole breadth one and three-fourths inches deep, going into the timber, and between the in end of chock and out end of block wedged keys are driven to prevent the block from moving and working back or forth. Crank, best fagoted iron, bossed seventeen and one-half inches diameter, ten inches deep; eye bored slightly under the ten-inch diameter, so that it can be shrunk on shaft, end bossed for crank pin to be eleven and one- fourth inches diameter, eight inches deep, bored six and three- fourth inches diameter at back, tapering to six and three-fourth inches front; the pin to be shrunk in; web at shaft end five by fourteen inches; at pin end four inches by eight and three- fourths inches. Crank pin six inches long; wrist five and one- half inches diameter by six inches long; key, two and one-half inches by seven-eighths inch, and fourteen inches long.

The whole of this specification is to be duplicated, for it only represents the engine and appurtenances for one side of the boat. The same kind of an engine is necessary for the other side of the boat, and connected at right angles with this one on the same shaft.

SPECIFICATIONS FOR AUXILIARY ENGINE.

Cylinder.- Diameter, eight inches; stroke, twenty-one inches; thickness, three-fourths inch below the flutes.

Length from face to face, two feet three and one-fourth inches.

Diameter of top and bottom flanges, thirteen and one-fourth inches; thickness, one and one-fourth bottom, fifteen-sixteenths top.

Diameter of branch inside, two and three-fourths inches; thickness, five-eighths inch.

Diameter of flanges for branch inside, seven and one-half inches; thickness, one inch.

Steam ports, one-half inch by two inches.

Bridges, one-half inch by two inches.

Exhaust port, one inch by two inches.

Steam chest, ten and seven-sixteenths inches long by eighth and one-half inches wide, outside; height, three and one-half inches.