Fig. 75 represents a stern-wheel launch, showing the arrangement of the machinery, steering. gear and the general design.

These launches are designed with special reference to their use on rivers and lakes where the depth of water prohibits the use of the propeller.

Their light draft, economy of construction, powerful machinery and consequent speed, render them very desirable for shallow waters.

The hulls of these launches should be built of the best material, in a thoroughly workman-like manner, so modelled as to give the greatest speed attainable with a light draft of water. An awning-deck overhead, supported on oak stanchions, should form a protection from the sun. and rain, while at the same time being free from the objections that pertain to a close cabin. The steering apparatus should be placed as shown, near the bow, thus enabling one person to make a landing with ease and convenience.

The machinery should consist of a submerged tube vertical boiler, complete in every respect, and complying wi h the Government rules and regulations relative to marine boilers. The engines, two in number, should be connected direct to the stern-wheel shaft, thus doing away with all intermediate friction, a necessary evil that exists when the stern-wheel is driven by means of gearing. They should be reversed and

controlled by a single lever and throttle-valve, in the same manner as all ordinary vertical launch engines.

In order to separate the passengers from the engine and boiler room, cross bulk-heads should be built into the hull, thus completely shutting them out. Between these two bulk-heads and on each side should be arranged the seats.

In operation they will be found exceedingly handy, speedy little boats.

30

Number of persons will carry with comfort.

Approximate speed, miles per hour. .

Approximate consumption of soft coal, per 10 hours, pounds.

Actual Horse Power with 70 pounds of steam.

Engines-two in number-diameter of cylinder, inches.

stroke, inches

Vertical boiler, diameter inches.

height, inches

Diameter of stern-wheel, feet.

400

ΙΟ

5

20

40

53

7

Although the screw-propeller has almost entirely superseded the paddle-wheel, as a mode of propelling sea-going steamships, the latter still maintains its place in river steamers, and in seagoing steamers of large power and light draft of

water.

Inasmuch as the propeller-wheel, to work efficiently, must be submerged, or nearly so, any increase in its size demands an increase in the draft of water, while a paddle-wheel can be increased by making it broader on the face, without increasing the dip of the floats; it follows, then, that where much power is required in combination with a light draft of water, the propellerwheel can not be used, and recourse must be had to paddle-wheels. For river service, in its two forms, namely, the stern-wheel and side-wheel, it still holds its own.

The magnificent floating palaces that ply upon our western rivers are, almost without exception, driven by one of these two forms; in fact, with the limited draft of water, it would be impossible to use any other known method of propulsion, and attain the speed for which these steamers are famous.

For inland waters, free from the disturbing influences of storms, this method of propulsion has many advantages. The enormous guards on side-wheel steamers, extending over the sides of the boats, give great carrying capacity, either for freight or passengers, while the light draft. of water permits a landing at any point along the shore, without injury to the hull.

It is conceded that, for passenger traffic, on rivers the side-wheel steamer, is best, and it may be said that there is no other form that combines

in so great a degree large carrying capacity with such small dimensions.

The propeller wheels on Willard's launches are made of the best selected cold-blast iron, and are of various forms, according to the use to which the launch is to be put. Where high speed is desired, they furnish a different wheel than for towing purposes. For very small

launches a two or three blade wheel will be found desirable, but for launches using wheels 30 inch or larger diameter, the writer would. recommend a four-blade wheel.

Fig. 77 shows the different styles of propeller wheels which are furnished with these launches. No. I is a towing wheel. No. 2 is a speed wheel; it has a little different shape and pitch than that used for towing. No. 3 is a three-blade speed wheel suitable for a small launch. No. 4 is a two-blade wheel suitable for a small launch, particularly where it is liable to run into grass or weeds, as it is less liable to get fouled than a three or four-blade wheel.