DREDGE FOR RUSSIAN GOVERNMENT FOR THE RIVER VOLGA

SYSTEM LINDON W. BATES (Soc. AN. J. COCKERILL, SERAING, BUILDERS)

THESE ARE THE LARGEST AND MOST POWERFUL DREDGES IN EXISTENCE. STEAM IS SUPPLIED ENTIRELY BY BABCOCK & WILCOX BOILERS
OF ABOUT 5600 HORSE-POWER

RUSSIAN GOVERNMENT DREDGES FIRED WITH NAPHTHA

A novel feature in the dredges shown in the accompanying photograph, which have been built by Messrs. La Société Anonyme John Cockerill of Seraing, for the Russian Government, is the installation of water-tube boilers. These are of the Babcock & Wilcox marine type, and have given on the trials very great satisfaction.

U. S. ARMY DREDGE NEW ORLEANS "-BABCOCK & WILCOX BOILERS, 3000 I. H. P

There are four of these boilers on each hull half, making eight in all, having a total heating surface of 17,200 square feet. In addition to this, a small boiler of the same construction is fitted in a stern-wheel steamer, which is to act as a workshop and general tender to the dredge; this boiler has 1000 square feet of heating surface.

On the Russian official trials, which took place on the 24th to 29th of May, 1900, the boilers worked throughout without a hitch, giving an abundance of perfectly dry steam. On the full power trial, with all the machinery running, no trouble was experienced in keeping the water level constant, or in getting a sufficiency of steam, although working at a very high rate of evaporation, which would be, judging from the indicated horse-power of the engine, nearly 8 pounds of water per square foot of heating surface per hour.

On the stern-wheel steamer, with the boiler of 1000 square feet heating surface, the boiler was forced to about double its rated capacity.

The boilers are fired exclusively with naphtha; there are four burners fitted to each boiler in the dredge, and two to the boiler in the stern wheeler.

The burners are made so as to swivel out from the furnace when requiring to be cleaned or examined. The spraying of the petroleum into the furnace is accomplished by a jet of steam. The oil by this means is atomized and made ready for combustion. The temperatures taken of

WORKING ON NEW YORK STATE BARGE CANAL. OWNERS: CROWELL, SHERMAN, STALTER Co.

BABCOCK

the funnel gases showed these to be very low, i. e., not more than about 500 degrees F.

One of the advantages derived from the use of these boilers is the small amount of weight, as compared with ordinary boilers. The weight of the four boilers on one hull half, complete in working order with funnel, uptakes, and all accessories, was .02 tons per indicated horse-power developed on the trial.

FUEL-ITS COMBUSTION AND ITS HEAT VALUE

T

HE term "fuel," in its widest sense, may mean any substance which, by its combination with oxygen, evolves heat. It is generally applied, however, to those substances which are in common every-day use for heat-producing purposes.

Coal is the fuel most extensively used, and while saw-dust, rice-chaff, bagasse, wood, etc., are not uncommon fuels for making steam on land, coal is practically the only solid fuel that need be considered in marine practice. The nature and quality of coal, in point of view of its heating value, vary considerably. It is a fossil of vegetable origin, and the difference in its nature is attributed to the variation in its origin. Coal from the same stratum does not vary in its nature or characteristics, and generally these characteristics are the same in a certain district, hence the district from which a certain coal is obtained usually determines its commercial designation.

Coal is divided into two main classes-anthracite and bituminous.

"Anthracite" is a word of Greek origin, meaning "carbon" or "coke," the fuel being so named probably because it is that which contains the largest percentage of fixed carbon.

"Bituminous" is of Latin origin, meaning "containing or resembling

bitumen."

There are various degrees in the nature of these coals, which may be enumerated as follows: Anthracite, or hard coal; semi-anthracite; semibituminous; bituminous, or soft coal; and lignite.

Pure anthracite coal-which is said to be the oldest and deepest formation--is found principally in the United States of America. It is also found in the western part of the South Wales coal fields; in the neighborhood of Swansea; in some parts of Scotland; to a small extent in France; in the South of Russia; and in the Osnabrück district of Westphalia, Germany.

Semi-anthracite coal closely resembles anthracite in its physical characteristics and appearance, but contains less fixed carbon and burns more freely. It is represented by what is known as "Welsh anthracite," and by coals from a limited territory in Pennsylvania.

Semi-bituminous coal is most largely represented by the "Cardiff" or "Welsh" coals from the enormous fields of South Wales, and in the United States by the rich deposits on the slope of the Appalachian Mountains, extending from Clearfield County, Pa., to the southern boundary of Virginia, the coals in this belt taking the names of "Pocahontas," "George's Creek," "Clearfield," etc. The Belgium coal, known as "Demigras," is also of this class.

Bituminous coal is found almost all over the world. The largest known