Memoir of John Ericsson

Memoir of John Ericsson

The "Nautical Chronicle" for 1805 contains an account of a "movable turning impregnable battery, invented by a Mr. Gillespie, a native of Scotland, who completed the model of a movable impregnable castle or battery, impervious to shot or bombs, provided with a cannon and carriage calculated to take a sure aim at any object." It is further stated that "the invention proposed will be found equally serviceable in floating batteries. Its machinery is adapted to turn the most ponderous mortars with the greatest ease, according to the position of the enemy." Again, the Transactions of the Society for the Promotion of Useful Arts in the State of New York, 1807, contains an illustration representing a side elevation of a circular revolving floating battery constructed by Abraham Bloodgood. The guns of this battery, as the inventor points out, "would be more easily worked than is common, as they would not require any lateral movement." It is also stated, as a peculiar feature of this floating battery, that "its rotary motion would bring all its cannon to bear successively, as fast as they could be loaded, on objects in any direction"; and that "its circular form would cause every shot that might strike it, not near the center, to glance." Thirty-five years after the publication of the illustration and description of the circular floating revolving tower of Abraham Bloodgood, Theodore R. Timby proposed to build a tower on land for coast defense, to be composed of iron, with several floors
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and tiers of guns, the tower to turn on a series of friction-rollers under its base. The principal feature of Timby's "invention" was that of arranging the guns radially within the tower, and firing each gun at the instant of its coming in line with the object aimed at during the rotary motion of the tower, precisely as invented by Bloodgood. About 1865 certain influential citizens presented drawings of Timby's revolving tower to the authorities at Washington, with a view of obtaining orders to build such towers for coast defense; but the plan was found to be not only very expensive, but radically defective in principle. The slides of the gun-carriages being fixed permanently in a radial direction within the tower, the guns, of course, are directed to all points of the compass. Hence, during an attack by a hostile fleet, with many ships abreast, only one assailant can be fired at, its companions being scot-free in the dead angle formed between the effective gun and the guns on either side. In the meantime the numerous guns, distributed round the tower on the several floors, cannot be fired until their time comes during the revolution of the tower. The enemy's fleet continuing its advance, of course, calls for a change of elevation of the pieces, which, considering the constant revolution of the tower and the different altitudes above the sea of the several tiers, presents perplexing difficulties. Nothing further need be said to explain why the Government did not accept the plans for Timby's revolving towers.

The origin of rotating circular gun-platforms being disposed of, the consideration of the central section of the illustration will now be resumed. It will be seen that the turret which protects the guns and gunners of the Monitor consists simply of a short cylinder resting on the deck, covered with a grated iron roof provided with sliding hatches. This cylinder is composed of eight thicknesses of wrought-iron plates, each one inch thick, firmly riveted together, the inside course, which extends below the rest, being accurately faced underneath. A flat, broad ring of bronze is let into the deck, its upper
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face being very smooth in order to form a water-tight joint with the base of the turret without the employment of any elastic packing, a peculiar feature of the turrets of the monitors, as will be seen further on. Unfortunately, before the Monitor left New York for Hampton Roads, it was suggested at the Navy Yard to insert a plaited hemp rope between the base of the turret and the bronze ring, for the purpose of making the joint perfectly water-tight. As might have been supposed, the rough and uneven hemp rope did not form a perfect joint; hence during the passage a great leak was observed at intervals as the sea washed over the decks. "The water came down under the turret like a waterfall," says Lieutenant Greene in his report. It will be proper to observe in this place that the "foundering" of the Monitor on its way to Charleston was not caused by the "separation of the upper and lower part of the hull," as was imagined by persons who possessed no knowledge of the method adopted by the builders in joining the upper and lower hulls. Again, those who asserted that the plates had been torn asunder at the junction of the hulls did not consider that severe strain cannot take place in a structure nearly submerged. The easy motion at sea, peculiar to the monitors, was pointed out by several of their commanders. Lieutenant Greene in his report to the Secretary of the Navy, dated on board the Monitor, March 27th, 1862, says with reference to sea-going qualities:

"During her passage from New York her roll was very easy and slow and not at all deep. She pitched very little and with no strain whatever."

Captain John Rodgers's report to the Secretary of the Navy, dated on board of the monitor Weehawken, January 22d, 1863, refers specially to the easy motion of his vessel:

"On Tuesday night, when off Chincoteague shoals, we had a very heavy gale from the E. N. E. with a very heavy sea, made confused and dangerous by the proximity of the land. The waves I measured after the sea abated; I found them twenty-three feet high. They were certainly seven feet higher in the midst of the storm. During the heaviest of the gale I stood upon the turret and admired the behavior of the vessel. She rose and fell to the waves, and I concluded that the monitor form had great sea-going qualities. If leaks were prevented no hurricane could injure her."

The true cause of the foundering of the Monitor was minutely explained to the writer some time after the occurrence by the engineer, a very intelligent person, who operated the centrifugal pumping-engine of the vessel at the time. According to his statement, oakum was packed under the base of the turret before going to sea, in order to make sure of a water-tight joint; but this expedient failed altogether, the sea gradually washing out the oakum in those places where it had been loosely packed, thereby permitting so large a
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quantity of water to enter under the turret, fully sixty-three feet in circumference, that the centrifugal pumping-engine had not sufficient power to expel it. The hull consequently filled gradually and settled, until at the expiration of about four hours the Monitor went to the bottom. It will be asked, in view of the preceding explanation of the construction of the monitor turrets, namely, that the smooth base of the turret forms a water-tight joint with the ring on the deck, why was oakum packed under the turret before going to Charleston? The commander of the vessel, Captain Bankhead, in his report of the foundering, adverts to the admission of water under the turret, but does not duly consider the serious character of the leak, sixty-three feet in length. Captain Bankhead evidently had not carefully investigated the matter when he attributed the accident to an imaginary separation of the upper and lower hull. [*] It should be observed, in justice to this officer, that having commanded the Monitor only during a brief period he possessed but an imperfect knowledge of his vessel, and probably knew nothing regarding the consequence of employing packing, -- namely, that it might cause "water to come down under the turret like a waterfall," as previously reported by the second officer in command. It is proper to mention as a mitigating circumstance in favor of the second officer, Lieutenant Greene, that previous to the battle in Hampton Roads he had "never performed any but midshipman duty." The important question, therefore, must remain unanswered, whether in the hands of an older and more experienced executive officer the Monitor, like the other vessels of her type, might not have reached Charleston in safety.

Referring again to the central part of the illustration [p. 733] and the sectional representation of the turret [above], it will be found that the guns are
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placed across the vessel; consequently only the end of the breech and upper part of the port-hole are seen. The object of the pendulum port-stoppers suspended under the roof is to afford protection to the turret crew while loading the guns. Generally, however, the turret should be moved, and the port-holes thereby turned away from the enemy. Much time was lost during the conflict with the Merrimac by closing the port-stoppers in place of merely moving the turret, the latter operation being performed by a small steamengine controlled by a single hand; while opening and closing the port-stoppers, as reported by Lieutenant Greene, required the entire gun-crew. The slow fire of the Monitor during the action, complained of by critics, was no doubt occasioned by an injudicious manipulation of the port-stoppers. There are occasions, however, when the turret should not be turned, in which case the port-stoppers are indispensable. The method adopted for turning the turret will be readily understood. The small steam-engine controlled by one man, before referred to, drives a double train of cog-wheels connected with the vertical axle of the turret, this axle being stepped in a bronze bearing secured to the central bulkhead of the vessel. The mechanism thus described was carefully tested before the Monitor left New York for Hampton Roads, and was found to move very freely, the turret being turned and the guns accurately pointed by the sailing-master without aid. The trouble reported by Lieutenant Greene regarding the manipulation of the turret was caused by inattention during the passage from New York, the working-gear having been permitted to rust for want of proper cleaning and oiling while exposed to the action of salt-water entering under the turret, from causes already explained.

Having thus briefly described the turret and its mechanism, our investigation of the central part of the sectional view of the battery will be completed by a mere reference to the steam-boilers placed aft of the turret. There are two of these boilers placed side by side, as shown in the cut on page 736. Two views being thus presented, the nature of the boilers will be understood without further explanation. It should be mentioned, however, that they proved very economical and efficient.

Aft Section. The following brief reference to this section of the sectional illustration, showing the motive engine, propeller, and rudder, will complete our description:

1. The motive engine, the construction of which is somewhat peculiar, consists of only one steam-cylinder with pistons applied at opposite ends, a steam-tight partition being introduced in the middle. The propeller-shaft has only one crank and one crank-pin, the difficulty of "passing the centers" being overcome by the expedient of placing the connecting-rods, actuated by the steam-pistons, at right angles to each other. Much space is saved within the vessel by employing only one steam-cylinder, an advantage of such importance in the short hulls of the monitors that the entire fleet built during the war was provided with engines of the stated type.

2. The propeller, being of the ordinary four-bladed type, needs no description; but the mode of protecting it against shot demands full explanation.
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Referring to the illustration, it will be seen that the under side of the overhang near the stern is cut out in the middle, forming a cavity needed to give free sweep to the propeller-blades; the slope of the cavity on either side of the propeller being considerably inclined in order to favor a free passage of the water to and from the propeller-blades.

3. The extreme beam at the forward side of the propeller-well is 31 feet, while the diameter of the propeller is only 9 feet; it will therefore be seen that the deck and side armor projects 11 feet on each side, thus protecting most effectually the propelling instrument as well as the equipoise rudder applied aft of the same. It will be readily admitted that no other vessel constructed here or elsewhere has such thorough protection to rudder and propeller as that just described.

The foregoing description of the hastily constructed steam-battery proves that, so far from being, as generally supposed, a rude specimen of naval construction, the Monitor displayed careful planning, besides workmanship of superior quality. Experts who examined the vessel and machinery after completion pronounced the entire structure a fine specimen of naval engineering.

The conflict in Hampton Roads, and the immediate building of a fleet of sea-going monitors by the United States Government, attracted great attention in all maritime countries, especially in the north of Europe. Admiral Lessoffsky, of the Russian navy, was at once ordered to be present during the completion and trial of our sea-going monitors. The report of this talented officer to his government being favorable, the Emperor immediately ordered a fleet of twelve vessels on the new system, to be constructed according to copies of the working-drawings from which the American sea-going monitors had been built. Sweden and Norway also forthwith laid the keels of a fleet of seven vessels of the new type, Turkey rapidly following the example of the northern European nations. It will be remembered that during the naval contest on the Danube the Russian batteries and torpedo-boats subjected the Turkish monitors to severe tests. England, in due course, adopted our turret system, discarding the turn-table and cupola.