of the bank of tubes, the steam and water of circulation entering the drum at the water line, the height of the water in the boiler being at the center

line of the drum.

This boiler was not adopted for stationary use until the latter part of the eighties, and then only in some European countries. Later, with some modifications, it has been extensively used in America as well as in Europe, and is now in very general operation in stationary plants.

The design was compact, and the desirability for marine work, for which purpose it was adapted by The Babcock & Wilcox Company in 1889.

reduced height added to its

for brick setting, and the general structure of the boiler materially reduced in weight.

In 1889, a boiler of this design, built for the steam yacht "Reverie," was made entirely of forged steel, and furnished steam at 225 pounds pressure to a quadruple-expansion engine having cylinders 8, 11, 161⁄2 and 26 inches in diameter by 12 inches stroke. The boiler contained 800 square feet of heating surface and 28 square feet of grate, the engine easily developing 250 indicated horse-power.

The success obtained with the "Reverie" boiler warranted the construction, on the same lines, of a larger boiler having 2263 square feet of heating surface and 53 square feet of grate. This boiler was sold to Messrs. Thomas Wilson & Sons, Hull, England, and installed in 1891 in their S. S. "Nero." The engines were of the triple-expansion type, with cylinders 14, 24 and 39%1⁄2 inches in diameter by 30 inches stroke. Steam of 200 pounds pressure was furnished by the boiler, the engine developing 500 indicated horse-power.

This vessel has since been in constant service; the economy and re

liability of the boiler proving so satisfactory to the owners that eight cargo and passenger ships have since been fitted for this firm.

In 1892 a boiler, designed to carry 250 pounds steam pressure, was built for and installed in the steam yacht Trophy." Both weight and space were saved by this change and the speed of the yacht materially increased.

In 1895 some slight changes were made in the construction of the Babcock & Wilcox boiler in order to increase accessibility. The vertical side tubes were replaced by forged steel boxes at the furnace sides, with tubes above, both boxes and tubes being inclined the same as the sections, the boiler taking the form shown in the cut. (See Babcock & Wilcox, 1895, opposite.)

Two boilers of this design were constructed for the 6000-ton lake freighter "Zenith-City," the vessel being the largest at that time ever built on fresh water.

The engines were of the triple-expansion type, with cylinders 22, 38 and 63 inches in diameter by 40 inches stroke of piston. These sizes were proportioned to economically expand steam of 225 pounds initial pressure; this pressure being 50 pounds in excess of the ordinary practice in connection with triple engines.

This first installation of water-tube boilers in the lake trade was due to the progressiveness of Captain A. B. Wolvin. He realized the full value of a device which would reduce the weight, space and cost of operation of the machinery plant of a freight steamer, without reduction of power. He is rightly entitled to be called the "pioneer" in the use of high-pressure steam, water-tube boilers and quadruple-expansion engines in cargo steamers on the Great Lakes, and has proved the potency of these factors by the great success with which large cargoes are handled in these waters.

In 1896, in order to facilitate general operation and render the drum fittings more accessible, the boiler was reversed in its relation to the fire-room, or stoked from the opposite end. The firing doors were placed under the cross box forming the mud drum, or blow-off connection, the location of the steam and water drum being at the front of the boiler, immediately overhead. At the same time the economizer previously located