“The French idea in mounting their heavy guns singly in three or four armored barbettes is evidently so to distribute the gun-power as to leave a reserve of heavy guns in event of damage to one or more. But the demands for economy in weight are so great that two armored structures widely separated would seem to furnish as satisfactory a scattering of the heavy gun-power as is justifiable. Guns mounted on the middle line suffer less disturbance in rolling than those mounted either in the waist or en échelon, and their fire should be correspondingly more accurate.”[18]
The Impérieuse and Warspite have powerful ram bows, a steel protective deck, and a belt of compound armor which is 139 feet in length on the water-line, 8 feet in width, and 10 inches thick. The engines were designed to develop 7500 horse-power and a speed of 16 knots, but on her trial the Impérieuse attained with forced draft a maximum speed of 18.2 knots and 10,344 horse-power, and a mean speed, after four runs on the measured mile, of 17.21 knots. In September, 1886, with all guns and stores in place, and with 900 tons of coal in the bunkers, the Impérieuse developed a mean speed of 16 knots. The armament is composed of four 9.2-inch guns, mounted in four 8-inch plated circular barbettes, and situated one forward, one aft, and two in the waist; on the gun-deck there are six 6-inch guns, and the secondary battery is made up of twelve 6-pounder rapid fire, ten 1-inch Nordenfeldt, and four Gardner guns, and of four above-water and two submerged torpedo-tubes. Owing to the increased weights of the armament, stores, machinery, and equipments put in these vessels since they were first designed, the draught of water is now found to be nearly three feet greater than was intended. It is only fair to state that they were originally expected to carry but 400 tons of coal, though curiously enough, when this fuel capacity was subsequently increased to 1200 tons, no allowance was made for the additional armored surface required.
The armored free-board was to have been 3 feet 3 inches at a draught of 25 feet, but the supplementary weights increased the draught 11½ inches and reduced this free-board to 2 feet 3½ inches; and later, when the full bunker capacity of 900 tons was utilized, the draught was again increased 14 inches, and the free-board lowered to 1 foot 1½ inches. Finally it was for a time determined to carry 1200 tons of coal, though this would result, when the ship was fully equipped for sea, in bringing the top of the armored belt nearly flush with the water.
“As four of the torpedo tubes are above water, and have ports cut through the armor-belt, this decrease of free-board rendered them useless, it having been shown during an experimental cruise on the Impérieuse in December, 1886, with but 800 tons of coal on board and in a calm sea, that in attempting to discharge the broadside torpedoes they jammed in the tubes, and altered shape to a dangerous degree. In order to make them of any use they will have to be restored to their intended height above the water-line. It is believed this can be accomplished by removing part of the superstructure, by dispensing with all top-hamper and its attendant supply of stores, equipments, etc., and by limiting the maximum coal supply to the bunker capacity of 900 tons. The masts are accordingly being removed from both vessels, leaving them but one signal mast stepped between the funnels, and fitted with a military top.”[19]
In May, 1886, the Warspite, when very light, developed with natural draft 7451 horse-power and a speed of 15½ knots on a consumption of 2.69 pounds of coal each hour per horse-power; and with forced draft 10,242 horse-power and a speed of 17¼ knots were obtained on a similar consumption of 2.9 pounds of coal.
In the minority report of the 1871 Committee on Designs Admiral Elliot and Rear-Admiral Ryder “strongly advocated the use of a protective deck in conjunction with other features, instead of side-armor, for protection to stability. The idea as regards cruisers was first carried out in the full-rigged ships of the English Comus class of 2380 tons displacement and 13 knots speed, launched in 1878, in which the engines, boilers, and magazines were covered by a horizontal 1½-inch steel deck placed below the water-line, the space immediately above containing cellular subdivisions.
“Then followed, in 1882, the Leander and her three sister bark-rigged vessels, which are a compromise between the speed of the Iris and the protection of the Comus. They are of 3750 tons displacement and 17 knots maximum speed; they carry ten 6-inch 4-ton B. L. R., and 725 tons of coal, and have a ‘partial protective deck,’ covering engines, boilers, and magazines, which is 1½ inches thick, and which bends down below the load water-line at the sides. Our new cruisers, the Chicago, Boston, and Atlanta, bear a closer resemblance to this type than they do to any other in respect of their protection. About this time the Chilian cruiser Esmeralda, of 3000 tons, appeared, having a protective deck complete from stem to stern-post, carrying an exceptionally heavy battery and coal supply, and withal attaining the unprecedented speed of 18.28 knots. Italy was not slow to perceive the advantages of this type, and accordingly bought an improved Esmeralda, the Giovanni Bausan, and at once commenced to build four others, the Vesuvio, Stromboli, Etna, and Fieramosca, each of 3530 tons. Japan ordered two improved Esmeraldas, the sister ships Naniwa-Kan and Tacachiho-Kan, from Armstrong, in England, and a similar vessel, the Unebi, in France, while England laid down a similar class, the Mersey and three others, and France a similar cruiser, the Sfax, of 4400 tons.”[20] The Unebi was a bark-rigged, twin-screw, protected steel cruiser of 3651 tons. Her armament consisted of four 9.45-inch breech-loaders on sponsons, six 5.9-inch breech-loaders in broadside, one 5.9-inch bow pivot, twelve rapid fire and two Nordenfeldt machine guns, and a supply of Whitehead torpedoes. In September, 1886, she developed with forced draft 7000 horse-power and an average speed of 18.5 knots during four runs over the measured mile. She sailed for Japan in November, 1886, with a French crew numbering seventy-eight men, left Singapore for Yokohama on December 3, 1886, and has never been seen nor heard of since. She is said to have been top-heavy, and to have rolled dangerously in a sea way.
The Naniwa-Kan, a steel cruiser, 300 feet in length and 46 feet in beam, has on an extreme draught of 19 feet 6 inches a displacement of 3730 tons; the steel hull is fitted with a double bottom under the engines and boilers, and has a strong protective deck, two to three inches thick, which extends from the ram to the stern-post, and carries its edges four feet below, and its crown one inch above, the load water-line. There are ten complete transverse and several partial water-tight bulkheads; the space between the protective and the main deck is minutely subdivided into compartments, which are utilized as coal-bunkers, store-rooms, chain-lockers, and torpedo-rooms; the conning-tower is protected by two inches of steel armor; and two ammunition hoists, three inches thick, lead from the shell-rooms to the loading towers at the breech of the two heavy guns. The armament consists of two 10-inch 28-ton breech-loading rifles on central pivots, with 2-inch steel screens, and of six 6-inch guns, with a secondary battery of two 6-pounder rapid fire, eight 1-inch Nordenfeldt, four Gardner guns, and four above-water torpedo tubes. The engines are of the horizontal compound type, situated in two compartments, one abaft the other, and there are six single-ended locomotive three-furnace boilers in two separate compartments, with athwartship fire-rooms; the indicated horse-power under a forced draft was 7650, and the maximum speed 18.9 knots. This has since been exceeded. The Mersey and her class—the Severn, Thames, and Forth—like the Naniwa are unarmored steel cruisers, with a complete protective deck, the horizontal portion of which is one foot above, and the inclined three inches below, the water-line. The main battery of these ships consists of two 8-inch guns, mounted on central pivots forward and abaft a covered deck which carries ten 6-inch guns; the secondary battery has ten 1-inch Nordenfeldt and two Gardner machine guns, and there are six above-water torpedo-tubes in broadside.
“The development of the Mersey design has resulted in the new English ‘belted cruisers,’ in which, to satisfy the demand for a water-line belt of armor, the displacement has been increased to 5000 tons.”