'N Engineering, at the present day, there are three vital factors to excel

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lence: strength, efficiency, economy; and the owner of the machine or structure who has learned that "the engineer is the man who can make a

dollar go farthest" is just as much interested in these factors as the engineer. As has been well said, "the ultimate aim of nearly all engineering work is to make a profit for the user, and, however admirable otherwise, if it fails in this respect, it is an engineering failure, just as much as a break down."

The object of this catalogue is to show to vessel owners, designing engineers, and naval architects, as well as all who have the installation and care of machinery, that the Babcock & Wilcox Marine Boiler fulfills perfectly the three requirements mentioned above as well as the many others demanded of the best boiler; and that its use will give the most complete satisfaction to the designer of hull and machinery, the user and supervisor, and finally the owner by a greater return for his investment.

In early editions of this catalogue, it was necessary to present the merits of the water-tube boiler as an argument, because not many were in use, and the installation was recent. Now, this is all changed. During the past fifteen years, nearly three million horse-power of Babcock & Wilcox boilers have been installed in naval and merchant steamers all over the world, so that there has been the most ample opportunity to test them out in every way and under all conditions. They are used not only in the dreadnoughts and fast cruisers of the navies and in fast mail steamers, but in cargo vessels, ferry-boats, fire-boats, and steam whalers. Their economy and efficiency are so high that they have set the mark which no other boiler has yet attained. In some cases there has been opportunity for direct comparison with Scotch boilers in regular service, where the boilers are in identical hulls with the same engines. In these cases, the average of many voyages over the same route has shown that the Babcock & Wilcox boilers are decidedly more economical in fuel, saving more than ten per cent.

The features of safety and minimum weight for very high pressures commended them for naval use more quickly than in the merchant marine; but the demand for great power to give high speeds has made the designers of the latter class realize that they cannot afford to be carrying around hundreds of tons uselessly in the old type of shell boilers which might be used to earn money by carrying cargo. The Babcock & Wilcox boiler is safer, lighter, easier to maintain, much more nearly immune from damage by carelessness, and is also more efficient than the shell boiler. When vessel owners realize these facts fully, they will be amazed that they continued to use the old type of heavy and less efficient boiler so long. In the following pages will be found complete data proving all these statements and showing the saving by the use of the Babcock & Wilcox boiler.

A BRIEF HISTORY OF THE WATER-TUBE BOILER

N 1804, about a century ago, Col. John Stevens built and operated upon the Hudson River a little steamboat, 68 feet long by 14 feet wide.

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The machinery of this vessel consisted of a single upright cylinder whose piston rod moved up and down a cross head, which in turn drove two cranks by means of connecting rods. From the cranks a pair of shafts led aft, and were fitted with twin screws.

Steam was supplied by one water-tube boiler, containing 100 tubes, 2 inches in diameter and 18 inches long. One end of each tube was fastened to a central water leg, the other end being closed. The hot gases passed around these tubes, the water being inside of them. This vessel attained a speed of seven miles an hour and was one of the earliest examples of the use of the watertube boiler for marine purposes.

STEVENS, 1804

In 1805, Stevens's eldest son, John Cox Stevens, realizing the disadvan

tages of a boiler containing tubes with closed ends, patented another form of water-tube boiler, which he described as follows:* "Suppose a plate of brass of I foot square, in which a number of holes are perforated, into each of which holes is fixed one end of a copper tube of about an inch in diameter and 2 feet long, and the other ends of these tubes inserted in like manner into a similar piece of brass; the tubes, to insure their tightness, to be cast in the plates. These plates are to be enclosed at each end of the pipes by a strong cap of cast-iron or brass, so as to leave a space of an inch or two between the plates, or ends of the pipes, and the cast-iron cap at each end. The caps at each end are to be fastened by screw bolts passing through them into the plates.

JOHN COX STEVENS, 1805

The necessary supply of water is

to be injected, by means of a forcing pump, into the cap at one end; and through a tube inserted into the cap at the other end, the steam is to be conveyed to the cylinder of the steam engine. The whole is then to be encircled in brick work or masonry in the usual manner, placed either horizontally or perpendicularly, at option."

The circulation was therefore forced or maintained by the feed pump, the steam that was formed in the tubes being conducted from the opposite space to the engine.

Stevens was led to the belief that water-tube boilers embodied the correct principles of construc

tion, from a series of experiments made in France in 1790 by M. Balamour, under the auspices of the Royal Academy of Sciences. Balamour states: "It has been found that, within a certain range, the elasticity of steam is nearly doubled by every addition of temperature equal to 30 degrees Fahrenheit. These experiments were carried no higher than 280 degrees, at which temperature the elasticity of steam was found equal to about four times the pressure of the atmosphere. By experiments which have been lately made by myself, the elasticity of steam at the temperature of boiling oil, which has been estimated at about 600 degrees, was found to equal forty times the pressure of the atmosphere (600 pounds to the square inch). It is obvious that to derive advantages from an application of this *"Growth of the Steam Engine," Thurston.

principle, it is absolutely necessary that the vessel or vessels for generating steam should have sufficient strength to withstand the great pressure from an increase of elasticity in the steam, but this pressure is increased or diminished in proportion to the capacity of the containing vessel.

"The principle, then, of this invention consists of forming a boiler by means of a system or combination of a number of small vessels, instead of using, as in the usual mode, one large one; the relative strength of the materials of which these vessels are composed increasing in proportion to the diminution of capacity."

WILCOX, 1856

Appreciating the advantages to be gained from this style of construction, Stephen Wilcox in 1856 further perfected Stevens's design by giving to the bank of tubes an inclination and placing overhead a steam and water drum which connected the spaces at each end of the tubes. The necessity for a forced circulation was at once overcome, the steam and water drum forming a reservoir of sufficient volume to maintain a steady water line and give dry steam for the engine.

Although this boiler was constructed entirely of wrought-iron, it contained a very objectionable feature that of flat stayed surfaces opposite the tube ends.

To avoid the use of such stayed surfaces, the now well-known serpentine header or corrugated manifold was substituted in 1873. These headers were first made of cast-steel, and later of cast-iron. They separated the tubes into sections, facilitated examination and repair, and gave to the boiler a flexibility to permit expansion due to sudden fluctuation in temperature.

In a boiler designed by Babcock & Wilcox in 1881, the longitudinal steam and water drum was placed crosswise and above the lower end