The steam is supplied by two circular return tube boilers, 9 feet 6 inches in diameter and 10 feet long, with two furnaces in each. The boilers, which are of steel throughout, except the tubes, are placed longitudinally, and are fitted with two pairs of the Martyn-Roberts patent safety valves. They have one steam dome between them. The total heating surface is 1,700 square feet, the total steam space is 330 cubic feet, and the working pressure 100 lb. per square inch. The fire pump is a Wilson's "Excelsior," with 10 inch steam cylinder and 8 inch water barrel. This powerful pump is in a special compartment of the fore hold, and will draw water from the bilge, sea, or either hold. A steam windlass and a double-handle winch are on deck as shown. On trial trip the engines of the Churchill indicated a maximum of 645.5 horse power, driving the vessel 10.495 knots per hour. The vessel is remarkable for diversity of uses, for heavy engine power in a small hull, and for general compactness of arrangement.--_Engineering_. * * * * * THREE-WAY TUNNELS. Mr. T.R. Cramton, who at the Southampton meeting of the British Association suggested a method of tunneling which, under certain conditions, seems of excellent promise, brought forward a suggestion at Southport for the construction of three-way tunnels. Now, the undoubted aim of all engineers is economy of construction and the securing of permanent advantages. Mr. Crampton maintains that the suggested system will give these, that three tunnels of, say, 17 ft. diameter, can be constructed cheaper than one of 30 ft. diameter. After describing Sir J. C. Hawkshaw's scheme for the ventilation of long tunnels, the three-way scheme was discussed. Three separate tunnels of 17 ft. diameter each, or 227 ft. area, are to be connected by large passages about midway of their length. These passages are without valves; in fact, free air passages. Between these midway connections and the ends, say again midway between, is formed a branch at right angles either above or below with separate openings from the branch into the other tunnels, such openings being provided with doors or valves quite clear of the main tunnel, any two of which may be closed, thus separating at this point the corresponding tunnels from the third. The branch is to be led to any convenient position where the exhustion apparatus can be placed. If two of the tunnels are left open to this branch, and the third one shut off from it by closing the doors, the vitiated air will be drawn from the two working tunnels, through the connecting branch, while fresh air will be partly sucked down the vertical shafts through their open ends and partly at the center tunnel, which is supplied by forcing air down the vertical shaft in communication with it, a stop or door being placed just outside of the bottom of the shaft so as to compel the air to flow to the center of the tunnel. It will be observed that no trains are