As at

and navigable streams in the country. present built they are so simple and easily managed that any person of ordinary intelligence can use one of them, and one man alone can fire and run a 30 or 33 foot boat without any assistance, provided the steering-wheel is placed just behind the engine.

Frequently a number of gentlemen associate together and buy a launch jointly for the use of their families, or several persons owning barges will club together and buy a small boat for towing all the barges. It is not uncommonly the case that one of these boats will earn its entire cost in one season, when used for hire on a small lake or river, where there are summer visitors.

YACHT BOILERS.

In selecting the proper form of boiler for at steam yacht due regard must be had to the form of the hull, and also to the kind of fuel to be used. It would not be advisable to use a vertical boiler of great power in a long, narrow hull, calculated for high speed, nor would it be well to adopt this form in localities where wood is the only available fuel.

Usually, however, the vertical boiler will be found most convenient for launch purposes.

SUBMERGED TUBE VERTICAL MARINE BOILERS.

*

Where boats are required for use in waters

* Fig. 68.

that are under United States marine supervision, it will be necessary to have boilers that conform in every respect to the United States marine laws. These require, among other things, that vertical boilers used for marine purposes should have submerged tubes. The fact that a boiler has passed Government inspection is the strongest guarantee of the quality of the material and workmanship, as the requirements are extremely rigid.

GENERAL DIMENSIONS OF YACHT AND LAUNCH VERTICAL, MARINE BOILERS,

Designed and Constructed by Chas. P. Willard & Co., Chicago.

The boilers with which launches are supplied should be so proportioned that they will stand very low in the boat, bringing the centre of gravity as low as possible. They ought to be found to be very quick and free-steaming boilers, and economical of fuel. These boilers should be built of charcoal hammered wrought iron or steel, and tested, by hydrostatic pressure, to 150 lbs. to the square inch.

Where required for navigation of waters under Government supervision, it will be necessary to have submerged tube vertical boilers, or the horizontal boilers.

No one thing connected with a steam launch

is of more importance than to have the boiler free from all defects. Only the best quality of iron or steel should be used in the construction of it, as it is desirable, particularly with small boats, that the working steam pressure should be as high as possible.

The two forms of launch boilers which we illustrate in this book will all be found to steam freely, without the very objectionable feature of priming. This difficulty is frequently encountered in small boilers used in launches, particularly in rough water, where the disposition to prime, in small boilers of faulty construction, when crowded up to their full steaming capacity, is aggravated by the slopping over of the water from the rolling of the boat, making it difficult to get dry steam.

Probably no form of horizontal boiler used in launches combines in so great a degree, strength, compactness and low centre of gravity, as the form of boiler illustrated herewith, which is called the "Clyde" or Scotch boiler. Fig. 69.

As will be seen by the figure, all the surfaces of the fire-box and the shell of the boiler are cylindrical, this being the strongest form in which the material can be put together. The fire-grate is placed in the large central tube, and the fire is entirely surrounded by water. The "Clyde" is a return-tubular boiler. The fire passes through the large central tube into the