Torpedo nets were a passive ship defensive device against torpedoes. They were in common use from the 1890s until the Second World War, they were superseded by torpedo belts. With the introduction of the Whitehead torpedo in 1873, the subsequent development of the torpedo boat, new means were sought to protect capital ships against underwater attacks. In 1876 the British Admiralty Torpedo Committee came up with a number of recommendations for combating torpedoes, which included "... nets of galvanised iron hung around each battleship from projecting 40 ft spars". Experiments were conducted in 1877, with HMS Thunderer becoming the first operational ship to be fitted with the nets. Torpedo nets could be hung out from the defending ship, when moored or otherwise stationary in the water, on multiple horizontal booms; each boom was fixed to the ship at one end at or below the edge of the main deck, by a steel pin that permitted the boom to be swung against the ship and secured when the ship sailed.
A series of such booms was so fixed at intervals along each side of the ship. When the ship was moored, the free ends of the booms could be swung out with the net hung on the outer ends, thus suspending the net at a distance from the ship equal to the length of the boom, all around the ship. With the net mounted, a torpedo aimed at the ship would hit the mesh net and explode at a sufficient distance from the hull to prevent serious damage to the ship. Early booms were made of wood 10 inches in diameter but increased in the 1880s to 12 inches; each boom weighed 20 to 24 long cwt and cost £28 to £30. In the House of Commons on 9 April 1888 Admiral Field, MP for Eastbourne, asserted that steel booms designed by William Bullivant were at least 5 long cwt lighter, one-third less expensive and "superior in many other respects", asked Lord George Hamilton, First Lord of the Admiralty whether the Committee on Torpedo Net Defence had recommended steel booms and whether the Admiralty would further test them.
In reply the First Lord claimed that steel booms doubled up on impact, were more vulnerable to accidental damage and were harder to repair aboard a ship, whereas wooden ones were easier to replace. His Lordship further stated that the steel booms that the Committee favoured were of a different type to those designed by Bullivant. On 21 June 1888 three Opposition Liberal MPs questioned the First Lord on whether wooden booms were the best choice for either effectiveness or cost. Admiral Field claimed that the Admiralty Torpedo Committee and Dockyard officials preferred steel booms as they weighed less than 10 long cwt and cost £20 to £22. Field alleged that in experiments since September 1886 wooden booms "invariably failed" and that steel booms were lighter and more effective. In reply the First Lord claimed that in five experiments, wooden booms had worked on all but one occasion and that steel booms would be more expensive; when questioned by James Picton, MP for Leicester, the First Lord agreed that wooden beams were heavier.
John Brunner, MP for Northwich, asked, opposing steel booms, so that Parliament might debate whether to dismiss them. The First Lord ended the discussion by retorting that "it was most improper that Questions should be put to him for the purpose of advertising inventions". About 1875 William Munton Bullivant had taken over the Wire Tramway Co, a manufacturer of wire and steel rope based in Millwall and turned it into Bullivant and Co; the company exhibited at trade events including the Naval and Submarine Exhibition of 1882. Bullivant developed not only steel torpedo nets but steel booms to suspend them from ships. In 1888 Admiral Field and other Liberal MPs offended the First Sea Lord by promoting Bullivant's products in the House of Commons. However, by the early 20th century, torpedo nets were referred to as "Bullivant type", they were made from 6 1⁄2-inch-diameter steel hoops linked by smaller hoops to form a mesh, with a weight of about one pound per square foot. These nets were projected from the sides of the ship on 40-foot-long wooden booms.
Extensive tests were conducted, with the nets proving capable of stopping the contemporary 14-inch-diameter torpedo without being damaged. A 16-inch torpedo with a 91-pound warhead proved capable of causing limited damage to the net. A heavier net was introduced in 1894 consisting of 2 1⁄2-inch hoops with a weight of five pounds per square foot; the adoption of these nets resulted in the introduction of the torpedo net cutter on the nose of torpedoes, either in the form of scissors in Japanese designs, or a French pistol-powered version. Heavier, denser nets used by the German and British navies were regarded as "torpedo-proof". In spite of fitting the major ships with anti-torpedo nets, close danger of war, the Russians did not deploy the nets during the Japanese destroyer torpedo attack on the Imperial Russian Navy stationed on a roadside of Port Arthur on 8 February 1904, the opening shots of the Russo-Japanese War. In other actions in the war, nets were used by the Russian battleship Sevastopol.
At the end of the siege of Port Arthur she was anchored outside the harbor in a position where she was sheltered from the fire of the Japanese batteries but became exposed to persistent attacks from torpedo boats. From 11 to 16 December 1904, Sevastopol was exposed to numerous night attacks; the Japanese deployed 30 torpedo-boats, of which two were lost, it was estimated that altogether 104 torpedoes were fired against the ship. One torpedo produced a leak in the torpedo room.
Marine steam engine
A marine steam engine is a steam engine, used to power a ship or boat. This article deals with marine steam engines of the reciprocating type, which were in use from the inception of the steamboat in the early 19th century to their last years of large-scale manufacture during World War II. Reciprocating steam engines were progressively replaced in marine applications during the 20th century by steam turbines and marine diesel engines; the first commercially successful steam engine was developed by Thomas Newcomen in 1712. The steam engine improvements brought forth by James Watt in the half of the 18th century improved steam engine efficiency and allowed more compact engine arrangements. Successful adaptation of the steam engine to marine applications in England would have to wait until a century after Newcomen, when Scottish engineer William Symington built the world's "first practical steamboat", the Charlotte Dundas, in 1802. In 1807, the American Robert Fulton built the world's first commercially successful steamboat known as the North River Steamboat, powered by a Watt engine.
Following Fulton's success, steamboat technology developed on both sides of the Atlantic. Steamboats had a short range and were not seaworthy due to their weight, low power, tendency to break down, but they were employed along rivers and canals, for short journeys along the coast; the first successful transatlantic crossing by a steamship occurred in 1819 when Savannah sailed from Savannah, Georgia to Liverpool, England. The first steamship to make regular transatlantic crossings was the sidewheel steamer Great Western in 1838; as the 19th century progressed, marine steam engines and steamship technology developed alongside each other. Paddle propulsion gave way to the screw propeller, the introduction of iron and steel hulls to replace the traditional wooden hull allowed ships to grow larger, necessitating steam power plants that were complex and powerful. A wide variety of reciprocating marine steam engines were developed over the course of the 19th century; the two main methods of classifying such engines are by connection mechanism and cylinder technology.
Most early marine engines had the same cylinder technology but a number of different methods of supplying power to the crankshaft were in use. Thus, early marine engines are classified according to their connection mechanism; some common connection mechanisms were side-lever, walking beam and direct-acting. However, steam engines can be classified according to cylinder technology. One can therefore find examples of engines classified under both methods. An engine can be a compound walking beam type, compound being the cylinder technology, walking beam being the connection method. Over time, as most engines became direct-acting but cylinder technologies grew more complex, people began to classify engines according to cylinder technology. More encountered marine steam engine types are listed in the following sections. Note that not all these terms are exclusive to marine applications; the side-lever engine was the first type of steam engine adopted for marine use in Europe. In the early years of steam navigation, the side-lever was the most common type of marine engine for inland waterway and coastal service in Europe, it remained for many years the preferred engine for oceangoing service on both sides of the Atlantic.
The side-lever was an adaptation of the earliest form of the beam engine. The typical side-lever engine had a pair of heavy horizontal iron beams, known as side levers, that connected in the centre to the bottom of the engine with a pin; this connection allowed a limited arc for the levers to pivot in. These levers extended, on the cylinder side, to each side of the bottom of the vertical engine cylinder. A piston rod, connected vertically to the piston, extended out of the top of the cylinder; this rod attached to a horizontal crosshead, connected at each end to vertical rods. These rods connected down to the levers on each side of the cylinder; this formed the connection of the levers to the piston on the cylinder side of the engine. The other side of the levers were connected to each other with a horizontal crosstail; this crosstail in turn connected to and operated a single connecting rod, which turned the crankshaft. The rotation of the crankshaft was driven by the levers—which, at the cylinder side, were driven by the piston's vertical oscillation.
The main disadvantage of the side-lever engine was that it was heavy. For inland waterway and coastal service and more efficient designs soon replaced it, it remained the dominant engine type for oceangoing service through much of the first half of the 19th century however, due to its low centre of gravity, which gave ships more stability in heavy seas. It was a common early engine type for warships, since its low height made it less susceptible to battle damage. From the first Royal Navy steam vessel in 1820 until 1840, 70 steam vessels entered service, the majority with side-lever engines, using boilers set to 4psi maximum pressure; the low steam pressures dictated the large cylinder sizes for the side-lever engines, though the effective pressure on the piston was the difference between the boiler pressure and the vacuum in the condenser. The side-lever engine was not suitable for driving screw propellers; the last ship built for transatlantic service that had a side-lever engine was the Cunard Line's pa
Horsepower is a unit of measurement of power, or the rate at which work is done. There are many different types of horsepower. Two common definitions being used today are the mechanical horsepower, about 745.7 watts, the metric horsepower, 735.5 watts. The term was adopted in the late 18th century by Scottish engineer James Watt to compare the output of steam engines with the power of draft horses, it was expanded to include the output power of other types of piston engines, as well as turbines, electric motors and other machinery. The definition of the unit varied among geographical regions. Most countries now use the SI unit watt for measurement of power. With the implementation of the EU Directive 80/181/EEC on January 1, 2010, the use of horsepower in the EU is permitted only as a supplementary unit; the development of the steam engine provided a reason to compare the output of horses with that of the engines that could replace them. In 1702, Thomas Savery wrote in The Miner's Friend: So that an engine which will raise as much water as two horses, working together at one time in such a work, can do, for which there must be kept ten or twelve horses for doing the same.
I say, such an engine may be made large enough to do the work required in employing eight, fifteen, or twenty horses to be maintained and kept for doing such a work… The idea was used by James Watt to help market his improved steam engine. He had agreed to take royalties of one third of the savings in coal from the older Newcomen steam engines; this royalty scheme did not work with customers who did not have existing steam engines but used horses instead. Watt determined; the wheel was 12 feet in radius. Watt judged. So: P = W t = F d t = 180 l b f × 2.4 × 2 π × 12 f t 1 m i n = 32, 572 f t ⋅ l b f m i n. Watt defined and calculated the horsepower as 32,572 ft⋅lbf/min, rounded to an 33,000 ft⋅lbf/min. Watt determined that a pony could lift an average 220 lbf 100 ft per minute over a four-hour working shift. Watt judged a horse was 50% more powerful than a pony and thus arrived at the 33,000 ft⋅lbf/min figure. Engineering in History recounts that John Smeaton estimated that a horse could produce 22,916 foot-pounds per minute.
John Desaguliers had suggested 44,000 foot-pounds per minute and Tredgold 27,500 foot-pounds per minute. "Watt found by experiment in 1782 that a'brewery horse' could produce 32,400 foot-pounds per minute." James Watt and Matthew Boulton standardized that figure at 33,000 foot-pounds per minute the next year. A common legend states that the unit was created when one of Watt's first customers, a brewer demanded an engine that would match a horse, chose the strongest horse he had and driving it to the limit. Watt, while aware of the trick, accepted the challenge and built a machine, even stronger than the figure achieved by the brewer, it was the output of that machine which became the horsepower. In 1993, R. D. Stevenson and R. J. Wassersug published correspondence in Nature summarizing measurements and calculations of peak and sustained work rates of a horse. Citing measurements made at the 1926 Iowa State Fair, they reported that the peak power over a few seconds has been measured to be as high as 14.9 hp and observed that for sustained activity, a work rate of about 1 hp per horse is consistent with agricultural advice from both the 19th and 20th centuries and consistent with a work rate of about 4 times the basal rate expended by other vertebrates for sustained activity.
When considering human-powered equipment, a healthy human can produce about 1.2 hp and sustain about 0.1 hp indefinitely. The Jamaican sprinter Usain Bolt produced a maximum of 3.5 hp 0.89 seconds into his 9.58 second 100-metre dash world record in 2009. When torque T is in pound-foot units, rotational speed is in rpm and power is required in horsepower: P / hp = T / × N / rpm 5252 The constant 5252 is the rounded value of /; when torque T is in inch pounds: P
France the French Republic, is a country whose territory consists of metropolitan France in Western Europe and several overseas regions and territories. The metropolitan area of France extends from the Mediterranean Sea to the English Channel and the North Sea, from the Rhine to the Atlantic Ocean, it is bordered by Belgium and Germany to the northeast and Italy to the east, Andorra and Spain to the south. The overseas territories include French Guiana in South America and several islands in the Atlantic and Indian oceans; the country's 18 integral regions span a combined area of 643,801 square kilometres and a total population of 67.3 million. France, a sovereign state, is a unitary semi-presidential republic with its capital in Paris, the country's largest city and main cultural and commercial centre. Other major urban areas include Lyon, Toulouse, Bordeaux and Nice. During the Iron Age, what is now metropolitan France was inhabited by a Celtic people. Rome annexed the area in 51 BC, holding it until the arrival of Germanic Franks in 476, who formed the Kingdom of Francia.
The Treaty of Verdun of 843 partitioned Francia into Middle Francia and West Francia. West Francia which became the Kingdom of France in 987 emerged as a major European power in the Late Middle Ages following its victory in the Hundred Years' War. During the Renaissance, French culture flourished and a global colonial empire was established, which by the 20th century would become the second largest in the world; the 16th century was dominated by religious civil wars between Protestants. France became Europe's dominant cultural and military power in the 17th century under Louis XIV. In the late 18th century, the French Revolution overthrew the absolute monarchy, established one of modern history's earliest republics, saw the drafting of the Declaration of the Rights of Man and of the Citizen, which expresses the nation's ideals to this day. In the 19th century, Napoleon established the First French Empire, his subsequent Napoleonic Wars shaped the course of continental Europe. Following the collapse of the Empire, France endured a tumultuous succession of governments culminating with the establishment of the French Third Republic in 1870.
France was a major participant in World War I, from which it emerged victorious, was one of the Allies in World War II, but came under occupation by the Axis powers in 1940. Following liberation in 1944, a Fourth Republic was established and dissolved in the course of the Algerian War; the Fifth Republic, led by Charles de Gaulle, remains today. Algeria and nearly all the other colonies became independent in the 1960s and retained close economic and military connections with France. France has long been a global centre of art and philosophy, it hosts the world's fourth-largest number of UNESCO World Heritage Sites and is the leading tourist destination, receiving around 83 million foreign visitors annually. France is a developed country with the world's sixth-largest economy by nominal GDP, tenth-largest by purchasing power parity. In terms of aggregate household wealth, it ranks fourth in the world. France performs well in international rankings of education, health care, life expectancy, human development.
France is considered a great power in global affairs, being one of the five permanent members of the United Nations Security Council with the power to veto and an official nuclear-weapon state. It is a leading member state of the European Union and the Eurozone, a member of the Group of 7, North Atlantic Treaty Organization, Organisation for Economic Co-operation and Development, the World Trade Organization, La Francophonie. Applied to the whole Frankish Empire, the name "France" comes from the Latin "Francia", or "country of the Franks". Modern France is still named today "Francia" in Italian and Spanish, "Frankreich" in German and "Frankrijk" in Dutch, all of which have more or less the same historical meaning. There are various theories as to the origin of the name Frank. Following the precedents of Edward Gibbon and Jacob Grimm, the name of the Franks has been linked with the word frank in English, it has been suggested that the meaning of "free" was adopted because, after the conquest of Gaul, only Franks were free of taxation.
Another theory is that it is derived from the Proto-Germanic word frankon, which translates as javelin or lance as the throwing axe of the Franks was known as a francisca. However, it has been determined that these weapons were named because of their use by the Franks, not the other way around; the oldest traces of human life in what is now France date from 1.8 million years ago. Over the ensuing millennia, Humans were confronted by a harsh and variable climate, marked by several glacial eras. Early hominids led a nomadic hunter-gatherer life. France has a large number of decorated caves from the upper Palaeolithic era, including one of the most famous and best preserved, Lascaux. At the end of the last glacial period, the climate became milder. After strong demographic and agricultural development between the 4th and 3rd millennia, metallurgy appeared at the end of the 3rd millennium working gold and bronze, iron. France has numerous megalithic sites from the Neolithic period, including the exceptiona
The Provence-class ironclads were a group of 10 armored frigates built for the French Navy during the 1860s. They were succeeded by the Ocean-class ironclads. Flandre Gauloise Guyenne Héroïne Magnanime Provence Revanche Savoie Surveillante Valeureuse de Balincourt, Captain. "The French Navy of Yesterday: Ironclad Frigates: Second Group – Provence Type". F. P. D. S. Newsletter. Akron, OH: F. P. D. S. III: 9–13. Chesneau, Roger & Kolesnik, Eugene M. eds.. Conway's All the World's Fighting Ships 1860–1905. Greenwich, UK: Conway Maritime Press. ISBN 0-8317-0302-4. Gille, Eric. Cent ans de cuirassés français. Nantes: Marines. ISBN 2-909-675-50-5. Silverstone, Paul H.. Directory of the World's Capital Ships. New York: Hippocrene Books. ISBN 0-88254-979-0
A deck is a permanent covering over a compartment or a hull of a ship. On a boat or ship, the primary or upper deck is the horizontal structure that forms the "roof" of the hull, strengthening it and serving as the primary working surface. Vessels have more than one level both within the hull and in the superstructure above the primary deck, similar to the floors of a multi-storey building, that are referred to as decks, as are certain compartments and decks built over specific areas of the superstructure. Decks for some purposes have specific names; the main purpose of the upper or primary deck is structural, only secondarily to provide weather-tightness and support people and equipment. The deck serves as the lid to the complex box girder, it resists tension and racking forces. The deck's scantling is the same as the topsides, or might be heavier if the deck is expected to carry heavier loads; the deck will be reinforced around deck fittings such as cleats, or bollards. On ships with more than one level, deck refers to the level itself.
The actual floor surface is called the sole, the term deck refers to a structural member tying the ships frames or ribs together over the keel. In modern ships, the interior decks are numbered from the primary deck, #1, downward and upward. So the first deck below the primary deck will be #2, the first above the primary deck will be #A2 or #S2; some merchant ships may alternatively designate decks below the primary deck machinery spaces, by numbers, those above it, in the accommodation block, by letters. Ships may call decks by common names, or may invent fanciful and romantic names for a specific deck or area of that specific ship, such as the Lido deck of the Princess Cruises' Love Boat. Equipment mounted on deck, such as the ship's wheel, fife rails, so forth, may be collectively referred to as deck furniture. Weather decks in western designs evolved from having structures fore and aft of the ship clear. Eastern designs developed earlier, with efficient middle decks and minimalist fore and aft cabin structures across a range of designs.
In vessels having more than one deck there are various naming conventions, alphabetically, etc. However, there are various common historical names and types of decks: 01 level is the term used in naval services to refer to the deck above the main deck; the next higher decks are referred to as the 02 level, the 03 level, so on. Although these are formally called decks, they are referred to as levels, because they are incomplete decks that do not extend all the way from the stem to the stern or across the ship. Afterdeck an open deck area toward the stern-aft. Berth deck: A deck next below the gun deck, where the hammocks of the crew are slung. Boat deck: Especially on ships with sponsons, the deck area where lifeboats or the ship's gig are stored. Boiler deck: The passenger deck above the vessel's boilers. Bridge deck: The deck area including the helm and navigation station, where the Officer of the Deck/Watch will be found known as the conn An athwartships structure at the forward end of the cockpit with a deck somewhat lower than the primary deck, to prevent a pooping wave from entering through the companionway.
May refer to the deck of a bridge. Flight deck: A deck from which aircraft take off or land. Flush deck: Any continuous unbroken deck from stem to stern. Forecastle deck: A partial deck above the main deck under which the sailors have their berths, extending from the foremast to the bow. Freeboard deck: assigned by a classification society to determine the ship's freeboard. Gun deck: on a multi-decked vessel, a deck below the upper deck where the ships' cannon were carried; the term referred to deck for which the primary function was the mounting of cannon to be fired in broadsides. However, on many smaller and unrated vessels the upper deck and quarterdeck bore all of the cannons but were not referred to as the gun deck. Hangar deck: A deck aboard an aircraft carrier used to store and maintain aircraft. Half-deck: That portion of the deck next below the forecastle or quarterdeck, between the mainmast and the cabin. Helicopter deck: Usually located near the stern and always kept clear of obstacles hazardous to a helicopter landing.
Hurricane deck:, the upper deck a light deck, erected above the frame of the hull. Lido deck: Open area at or near the stern of a passenger ship, housing the main outdoor swimming pool and sunbathing area. Lower deck: the deck over the hold, orig. only of a ship with two decks. Synonym for berth deck. Alternative name for a secondary gun deck Main deck: The principal deck of a vessel. Middle or Waist deck the working area of the deck. Orlop deck: The deck or part of a deck where the cables are stowed below the waterline, it is the lowest deck in a ship. Poop deck: The deck forming the roof of a poop or poop cabin, built on the upper deck and extending from the mizzenmast aft. Promenade deck: A "wrap-around porch" found on passenger ships a
USS Dunderberg, a Swedish word meaning "thunder mountain," was an ocean-going casemate ironclad of 14 guns. She resembled an two-masted version of the Confederate casemate ironclad CSS Virginia, she was designed to have both gun turrets and a casemate but the turrets were deleted while the ship was still being built. Construction began in 1862, but progress was slow and she was not launched until after the end of the American Civil War in 1865; the ship was not accepted by the Union Navy. She was placed in reserve, but was mobilized in 1870 to participate in the Franco-Prussian War; the ship was decommissioned after the end of the war. Rochambeau was stricken from the Navy List in 1872 and scrapped in 1874. On 11 April 1862, William H. Webb, arguably the premier wooden shipbuilder in the country, sent a model of a large wooden-hulled, casemate ironclad with a displacement of about 7,000 long tons to the US Navy Department. Webb signed a contract on 3 July with the Navy's Bureau of Yards and Docks for a ship that had an overall length of 350 feet, a beam of at least 68 feet and a draft of no more than 20 feet 6 inches.
His ship was required to make 15 knots in still water and she was to be armed with four 15-inch Dahlgren guns in two gun turrets, each protected by 11 inches of armor, eight 11-inch Dahlgren guns in a casemate. The ship was to be completed in 15 months at a cost of $1,250,000. Dunderberg's contract, as the ship was now named by Webb, was amended on 27 August to specify her armor scheme. Above the main deck, her armor was to be 4.5 inches thick. From the main deck to a depth of 5 feet below the waterline, the armor was to be 3.5 inches thick, tapering to 2.5 inches at its lower edge. The ship's main and casemate deck armor was.75 inches thick except at the rear of the ship. The main deck, from the rear of the casemate to the stern, was to consist of 4.5-inch armor plates that tapered to 2.5 inches in thickness. Dunderberg was to be given a complete double bottom and her engine and boiler rooms were to be enclosed by watertight bulkheads, she was to be provided with two masts and the appropriate rigging.
The ship was powered by two back-acting steam engines driving one four-bladed propeller 21 feet feet in diameter, using steam generated by six tubular boilers at a working pressure of 25 psi. The engines, designed to produce 4,500 indicated horsepower, boilers were both subcontracted by Webb to the Etna Iron Works of New York City; the engines were intended to have a bore of 90 inches and a stroke of 45 inches, but Webb increased the bore to 100 inches to insure that Dunderberg reached her contract speed. During the ship's first sea trial on 22 February 1867, she reached a speed of about 12.5 knots. She had two auxiliary boilers to provide steam for the steam engines that powered her pumps, ventilation fans and rotated the gun turrets; these engines, with their bore and stroke of 36 inches, were larger than the main engines of the Passaic-class monitors. All of the boilers exhausted through a retractable funnel; the ship carried 540 long tons of coal, but could hold a maximum of 1,000 long tons.
She had a light brigantine rig. Her keel was laid down before 3 October 1862 at Webb's shipyard in New York City though Webb was forced to use unseasoned oak for Dunderberg because the supply of seasoned timber had been exhausted earlier in the war. Unseasoned wood was far more prone to rot and shortened the ship's life, her hull was strongly built with the space between her frames filled with timber and diagonal iron straps tied her frames together. The sides of the casemate at the level of the main deck were 5 feet thick. Before beginning construction, Webb redesigned the hull, increasing its length to 358 feet 8 inches between perpendiculars and its overall length to 377 feet 4 inches, her beam decreased from 75 feet 6 inches to 72 feet 10 inches and she displaced, at her nominal draft of 18 feet forward and 21 feet aft, 6,948 long tons. These changes made her the longest wooden ship built. Dunderberg's hull was protected from biofouling by two external layers of copper; the ship was fitted with two rudders, the primary one in the usual location aft of the propeller, but she had an auxiliary rudder placed in the deadwood above and ahead of the propeller.
Many other changes were made to Dunderberg while she was under construction and contributed to her delays in completion. The most important of these was the eventual elimination of her turrets which began in October 1863 when Webb wrote to Gideon Welles, Secretary of the Navy, saying that he concurred with the General Superintendent of Ironclads, Rear Admiral Francis Gregory's suggestion that the "turrets be dispensed with and the casemate lengthened to accommodate an additional number of guns" Welles did not approve the change until September 1864 when he authorized an armament of four 15-inch and twelve 11-inch guns in the casemate; this was extended by 73 feet to an approximate overall length of 228 feet so that it now covered the aft magazine and shell