Size of arms at outside of flange four and one-half inches wide, tapering to three and one-half inches at the ends; thickness one inch, to be bolted into the sockets in the flange by three 7/8- inch square bolts. The wheel to have two rims running over it, between the flange and the bucket, of wrought-iron three inches broad by five-eighths inch thick, fastened to each arm with clamp three-fourths inch; buckets to be fastened to the arms in the usual way; face of buckets thirty inches, with three stirrups in a bucket at each arm, with plate on front side; arms of sufficient length to make the wheel twenty-two feet in diameter. There is to be a throttle-valve chamber, with proper flanges for connecting steam pipes to run from the center of the boat to each engine on the outside, with flanges for each side of steam pipe for the auxiliary engine connections and feeder for heater; the area of valve vent to be equal to both the areas of the others; other parts the same as described in the relief valve above mentioned.

All the journals and moving parts of the engines and cylinders to by supplies with suitable oil-cups and cocks and all working parts. Cylinders to have in each end suitable cocks to let condensed steam out, and all side and steam pipes to be supplies with cocks where there is any bend that the water would settle.

Boilers.- There are to be five boilers, thirty-six inches diameter and twenty-four feet long, with five 7 1/2-inch flues inside each boiler. thickness, sides 5/16-inch, head 12/16-inch; flanges upon one end the flue to fit against the outside of the head of the boiler, and upon the other the flanges are to be turned from the head outside to fit the flues. Upon the top and upon each boiler is to be placed a connection, five inches diameter inside, and bent so as to carry the steam horizontally back to the steam drum, and connecting with the drum upon the top. The connecting pipes are each to have a stop-valve, so that the steam can be cut off at pleasure. The steam drum is to be placed in the rear of the boiler, at a distance of three feet from the boilers; top of steam drum the same height as the boilers; diameter of drum twenty-four inches inside, length sixteen and one-half feet; thickness: sides same as boilers, with valve connections for supplying the boilers with water. The water connections to be supplied with stop-valves, as mentioned in steam connections. The other mud heater to be placed immediately aft of the fire-box, with like connections, omitting the water connections. In one end of this heater there is to be placed a blow-off valve, with steam and hand wheel for emptying boilers, all with properhand hole and plates. The whole to be supplied with proper man and hand hole plates in the boilers, mud heaters, and steam drum. The whole to be made of the best American charcoal iron, and to be double riveted in all seams that do not come in immediate contact with the fire, and to be calked on both sides where practicable. No acid or other injurious matter to be used in the joints or seams. Upon the after side of the steam drum there is to be made a proper connection for connecting a steam pipe eight inches diameter inside, the connection to be made in the center of the drum. Upon each of the boilers adjoining the center one there is to be placed a safety-valve, three and one-half inches