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coal-fired steam boilers. The boilers are designed ample-sized and easily fired, so that they can be run economically on any class of steam coal.

CARGO GEAR. A very important part of the equipment of a modern cargo ship is that for dealing with the cargo. Large strong derricks, or cranes, are fitted at each hatchway with quick-acting, powerful winches. Rapid loading and unloading saves much time in port, and enables the ship to start on a new voyage as soon as possible. Mechanical devices have been designed for the handling of certain bulk cargoes, such as coal, ore, grain, etc.

Oil Tanker.

Oil tankers come under the generic term of " tramp," as they are designed only for the carrying of a commodity, but they are actually a very special class in themselves, as they are built solely for the transport of one particular article, viz. oil in bulk. In general, they are of similar design to the ordinary tramp, but have many noteworthy distinctive features. They have more bulkheads, subdividing the ship into more compartments, as it is not desirable to carry oil in individually large spaces. The steel work has all to be specially arranged for this work and the riveting is more closely spaced than for ordinary watertight work, as oil is much more penetrating than water. The necessary pumping arrangements are very elaborate, and require very special attention. Cofferdams, or "idle spaces," have to be provided between all oil spaces, and other compartments, particularly the machinery spaces, to prevent fire or explosion through oil leakage.

Passenger Liners.

We now come to the last class of steamers, and these are the largest of all, viz. the steamers built specially for the conveyance of passengers and mails on the great highways of the ocean. Only in cases of joining up the great centres of population can the carriage of passengers be made the principal concern with any possibility of success as a commercial proposition. Thus, the most outstanding route for large, fast passenger ships is the North Atlantic. This has become, owing to many circumstances, very special in itself. Of all main passenger routes, the North Atlantic is the most

unfavourable from the weather standpoint, and, consequently, the ships engaged are all particularly strong and fit. The volume of traffic between Europe and North America, these two greatest centres of the civilized world, is so great and constant that a large fleet has now been built up to cope with it, and competition both between companies and countries is so keen that the services are run like a railway system for regularity and reliability. This has necessitated the building of very large and high-powered boats, and in no branch of shipping has the development, as regards both size and performance, been so rapid. It is little over a hundred years since the first steamship, the s.s. Savannah, of 320 tons, crossed the Atlantic, and now we have the great Majestic of over 50,000 tons. The Atlantic ships are the highest powered and the fastest on all the seas. This is contributed to very largely by the fact that fuel can be carried sufficient for the whole trip, whereas in the case of ships going East to India and China, or to Australia, South Africa and South America, re-bunkering en route is necessary, and it could not possibly pay to run high-powered, and, therefore, high consumption ships. Steam coal has to be taken from this country to intermediate ports for these ships, and the amount required must be kept within reasonable limits. For all these reasons we find that, whilst the North Atlantic ribbon is held by the Aquitania, steaming over 25 knots, and the average first-class ship steams 20, the ships plying on other routes seldom exceed 16 knots. Besides the largest passenger ships, there are on the North Atlantic route a great fleet of intermediate ships, i.e. to carry passengers and cargo. Speed must always be paid for, and the fares are always much higher on the purely passenger carrying vessel than on the intermediate also carrying cargo, and whilst there is a large traffic available for the large ships, there is also a large passenger traffic to whom the more moderate ship is desirable.

A diagram is reproduced, Fig. 5, showing the profile arrangement of decks, bulkheads, hatches, and accommodation in a typical modern passenger liner.

Sailing Ships.

These have a very limited sphere at the present day. According to Lloyd's Register latest returns, they constitute about 5 per cent

of the world's tonnage, and this continues a decreasing quantity. They were at the zenith of their power and popularity in the sixties and seventies of last century. The famous tea clippers, built in the United States of America and in the United Kingdom, were able to make the run from China to London at an average speed of about 15 knots. This run was, naturally, via the Cape of Good Hope.

In the early seventies, however, after the opening of the Suez Canal and the introduction of the multiple expansion reciprocating steam engine, the steamer's more economical performances made it impossible for the sailing ship to compete, and since then the number has slowly decreased.

Auxiliaries.

Sailing ships fitted with a moderate powered engine are generally called auxiliaries, and it is the opinion of some that, when the internal combustion engine becomes more reliable, this type will increase to compete in suitable trades and routes where sail can be used most of the time, and the auxiliary power in calm weather, restricted waters, and in and out of port.

General.

In addition to the main types of vessels outlined in the foregoing pages, there are many highly specialized ships built for very particular work. They all deserve attention, but in a book of this description it is not possible to deal with them in detail. Included under this heading there are dredgers, floating docks, salvage boats, river and lake steamers, fishery cruisers, yachts, tenders, etc.