Boatswain's call
A boatswain's call, pipe or bosun's whistle is a pipe or a non-diaphragm type whistle used on naval ships by a boatswain. It is pronounced, sometimes spelled, "bosun's call"; the pipe consists of a narrow tube. The player closes the hand over the hole to change the pitch; the rest of the pipe consists of a "keel", a flat piece of metal beneath the gun that holds the call together, the "shackle", a keyring that connects a long silver or brass chain that sits around the collar, when in ceremonial uniform. The boatswain's call was used to pass commands to the crew when the voice could not be heard over the sounds of the sea; because of its high pitch, it could be heard over the activities of bad weather. It is now used in traditional bugle calls such as Evening Colors/Sunset, in other ceremonies in most modern navies, it is sometimes accompanied by other auditive features such as ruffles and flourishes, voice commands and announcements, or a gun salute. It is the official badge of the Quartermaster, Chief Boatswain's Mate, Boatswain's Mate and in the Sea Cadets.
Pipe aboard: Flag-rank officers or an important guest is boarding a Navy ship. This is part of a ceremony called "manning the side" which includes a party of sailors known as "side boys", it has its origins in the need to hoist visiting senior officers aboard using a bosun's chair when the weather was too rough for the use of ladders. The bosun would use his call to direct the side boys in the hoisting of the chair; the following are the commands. Haul: The most basic of calls. Crews of warships were not allowed to sing work songs or shanties, so the pipe coordinated the sailors; the low note was for the pause and preparatory. The Side or Away Galley: Descends from the tradition of hoisting officers aboard ship in a chair, it is a combination of haul, a command to lower. This call remains in use as an honour given to officers when disembarking. Away Boats: Used to order a ship's boats to leave the ship's side. Call the Boatswain's Mates: The boatswain's gang to report. All Hands on Deck: Crews were split into three rotating watches that stood for two to four hours at a time.
This call signals the entire crew to assemble on deck. Word to be Passed: Command for silence, an order to follow. Pipe Down: Dismissal of all the crew not on watch. Sweepers. End of the work day. Ostensibly sailors would "sweep up" prior to departure in preparation for the following day. Pipe to any meal: Pipe All Hands, followed by long Heave Around, long Pipe Down. Still: Used to call the crew to attention; this would be done, for example, when two warships meet, the still being piped as the junior ship salutes the senior ship. Carry On: Used after the still, to dismiss the crew back to their duties. General Call: Piped before an announcement. Officer of the Day: Call the Officer of the Day to the Gangway; the Boatswain's Call – Photos and Diagrams ReadyAyeReady.com Bosun's Call MP3s by the US Navy Band A guide to the Robert S. Benner photographs of boatswains' whistles, 1976–1995
Robert Smith (Cabinet member)
Robert Smith was the second United States Secretary of the Navy from 1801 to 1809 and the sixth United States Secretary of State from 1809 to 1811. He was the brother of Senator Samuel Smith. Smith was born in Lancaster in the Province of Pennsylvania. During the American Revolutionary War, he served in the Continental Army and participated in the Battle of Brandywine, he began to practice law in Maryland. Smith became a Presidential Elector in the Electoral College for Maryland in 1789 a member of the state's senate from 1793 to 1795, a member of Maryland's house of delegates from 1796 to 1800. President Thomas Jefferson appointed him as Secretary of the Navy in July 1801 after William Jones declined the position. On March 2, 1805, the Senate confirmed the appointments of Smith as United States Attorney General and Jacob Crowninshield as Secretary of the Navy. However, Crowninshield declined his appointment, so Smith served as both Attorney General and Secretary of the Navy. President Jefferson appointed John Breckinridge to replace Smith as Attorney General and Smith resumed his role as a full-time Secretary of the Navy.
Smith left the office of Secretary of the Navy with the end of President Jefferson's administration on March 4, 1809. Jefferson's successor, President James Madison appointed Smith as Secretary of State, an office which he held from March 6, 1809, until his forced resignation on April 1, 1811. Smith was allied with his brother, Maryland Senator Samuel Smith, he bitterly opposed Treasury Secretary Albert Gallatin. Madison thought he could be his own Secretary of State, but Smith so pursued opposite policies that Madison demanded his resignation. In Madison's April 1811 "Memorandum on Robert Smith" the president offered a laundry list of Smith's shortcomings: he questioned Smith's loyalty. Smith was bewildered by these and other charges leveled by Madison and published an exoneration of himself, "Robert Smith's Address to the People of the United States," an attack on Madison's foreign policy. Madison offered Smith the post of ambassador to Russia then held by John Quincy Adams. Smith considered the offer.
Smith became the president of the not-yet-fully-organized American Bible Society in 1813. In 1818, he became the founding president of the Maryland Agriculture Society and afterwards retired to a more private life where he enjoyed his wealth. Robert Smith died in Baltimore, Maryland, on November 26, 1842; the USS Robert Smith was named for him. Clifford Egan, "Robert Smith" in Edward S. Mihalkanin, ed. American Statesmen: Secretaries of State from John Jay to Colin Powell, Greenwood Press 2004, pp. 478–83. Robert Smith at Find a Grave Robert Smith at the Naval Historical Center Robert Smith at the United States Department of State Robert Smith at the Hall of the Secretaries of State
Fresh water
Fresh water is any occurring water except seawater and brackish water. Fresh water includes water in ice sheets, ice caps, icebergs, ponds, rivers and underground water called groundwater. Fresh water is characterized by having low concentrations of dissolved salts and other total dissolved solids. Though the term excludes seawater and brackish water, it does include mineral-rich waters such as chalybeate springs. Fresh water is not the same as potable water. Much of the earth's fresh water is unsuitable for drinking without some treatment. Fresh water can become polluted by human activities or due to occurring processes, such as erosion. Water is critical to the survival of all living organisms; some organisms can thrive on salt water, but the great majority of higher plants and most mammals need fresh water to live. Fresh water can be defined as water with less than 500 parts per million of dissolved salts. Other sources give higher upper salinity limits for e.g. 1000 ppm or 3000 ppm. Fresh water habitats are classified as either lentic systems, which are the stillwaters including ponds, lakes and mires.
There is, in addition, a zone which bridges between groundwater and lotic systems, the hyporheic zone, which underlies many larger rivers and can contain more water than is seen in the open channel. It may be in direct contact with the underlying underground water; the majority of fresh water on Earth is in ice caps. The source of all fresh water is precipitation from the atmosphere, in the form of mist and snow. Fresh water falling as mist, rain or snow contains materials dissolved from the atmosphere and material from the sea and land over which the rain bearing clouds have traveled. In industrialized areas rain is acidic because of dissolved oxides of sulfur and nitrogen formed from burning of fossil fuels in cars, factories and aircraft and from the atmospheric emissions of industry. In some cases this acid rain results in pollution of rivers. In coastal areas fresh water may contain significant concentrations of salts derived from the sea if windy conditions have lifted drops of seawater into the rain-bearing clouds.
This can give rise to elevated concentrations of sodium, chloride and sulfate as well as many other compounds in smaller concentrations. In desert areas, or areas with impoverished or dusty soils, rain-bearing winds can pick up sand and dust and this can be deposited elsewhere in precipitation and causing the freshwater flow to be measurably contaminated both by insoluble solids but by the soluble components of those soils. Significant quantities of iron may be transported in this way including the well-documented transfer of iron-rich rainfall falling in Brazil derived from sand-storms in the Sahara in north Africa. Saline water in oceans and saline groundwater make up about 97% of all the water on Earth. Only 2.5–2.75% is fresh water, including 1.75–2% frozen in glaciers and snow, 0.5–0.75% as fresh groundwater and soil moisture, less than 0.01% of it as surface water in lakes and rivers. Freshwater lakes contain about 87% of this fresh surface water, including 29% in the African Great Lakes, 22% in Lake Baikal in Russia, 21% in the North American Great Lakes, 14% in other lakes.
Swamps have most of the balance with only a small amount in rivers, most notably the Amazon River. The atmosphere contains 0.04% water. In areas with no fresh water on the ground surface, fresh water derived from precipitation may, because of its lower density, overlie saline ground water in lenses or layers. Most of the world's fresh water is frozen in ice sheets. Many areas suffer from lack of distribution such as deserts. Water is a critical issue for the survival of all living organisms; some can use salt water but many organisms including the great majority of higher plants and most mammals must have access to fresh water to live. Some terrestrial mammals desert rodents, appear to survive without drinking, but they do generate water through the metabolism of cereal seeds, they have mechanisms to conserve water to the maximum degree. Fresh water creates a hypotonic environment for aquatic organisms; this is problematic for some organisms with pervious skins or with gill membranes, whose cell membranes may burst if excess water is not excreted.
Some protists accomplish this using contractile vacuoles, while freshwater fish excrete excess water via the kidney. Although most aquatic organisms have a limited ability to regulate their osmotic balance and therefore can only live within a narrow range of salinity, diadromous fish have the ability to migrate between fresh water and saline water bodies. During these migrations they undergo changes to adapt to the surroundings of the changed salinities; the eel uses the hormone prolactin, while in salmon the hormone cortisol plays a key role during this process. Many sea birds have special glands at the base of the bill; the marine iguanas on the Galápagos Islands excrete excess salt through a nasal gland and they sneeze out a salty excretion. Freshwater molluscs include freshwater snails and freshwater bivalves. Freshwater crustaceans include crayfish. Freshwater biodiversity faces many threats; the World Wide Fund for Nature's Living Planet Index noted an 83% decline in the populations of freshwater vertebrates between 1970 and 2014.
These declines continue to outpace
Rum ration
The rum ration was a daily amount of rum given to sailors on Royal Navy ships. It was abolished in 1970 after concerns that regular intakes of alcohol would lead to unsteady hands when working machinery; the rum ration, or "tot", from 1850 to 1970 consisted of one-eighth of an imperial pint of rum at 95.5 proof, given out to every sailor at midday. Senior ratings received their rum neat, whilst for junior ratings it was diluted with two parts of water to make three-eighths of an imperial pint of grog; the rum ration was served from one particular barrel known as the "Rum Tub", ornately decorated and was made of oak and reinforced with brass bands with brass letters saying "The Queen, God Bless Her". Not all sailors drew their rum: each had the option to be marked in the ship's books as "G" or "T". Sailors who opted to be "T" were given three pence a day instead of the rum ration, although most preferred the rum; the time when the rum ration was distributed was called "Up Spirits", between 11 am and 12 noon.
A common cry from the sailors was "Stand fast the Holy Ghost". This was in response to the bosun's call "Up Spirits"; each mess had a "Rum Bosun" who would collect the rum from the officer responsible for measuring the right number of tots for each mess. The officers did not get a rum ration. Tot glasses were kept separate from any other glasses, they were washed on the outside, but never inside, in the belief that residue of past tots would stick to the side of the glass and make the tot stronger. Sailors under 20 were not permitted a rum ration, were marked on the ship's books as "UA". A sailor's ration of alcohol was beer with a daily ration of one gallon; this official allowance continued until after the Napoleonic Wars. When beer was not available, as it would spoil it could be substituted by a pint of wine or half a pint of spirits depending on what was locally available. In years, the political influence of the West Indian planters led to rum being given the preference over arrack and other spirits.
The half pint of spirits was issued neat. The practice of compulsorily diluting rum in the proportion of half a pint to one quart of water was first introduced in the 1740s by Admiral Edward Vernon; the ration was split into two servings, one between 10 am and noon and the other between 4 and 6 pm. In 1756 Navy regulations required adding small quantities of lemon or lime juice to the ration, to prevent scurvy; the rum itself was procured from distillers in Jamaica, Trinidad & Tobago and the British Virgin Islands. Rations were cut in half in 1823 and again in half, to the traditional amount, in 1850; the abolition of the rum ration had been discussed in Parliament in 1850 and again in 1881 however nothing came of it. In 1970, Admiral Peter Hill-Norton abolished the rum ration as he felt it could have led to sailors failing a breathalyser test and being less capable to manage complex machinery; this decision to end the rum ration was taken after the Secretary of State for Defence had taken opinions from several ranks of the Navy.
Ratings were instead allowed to purchase beer, the amount allowed was determined, according to the MP David Owen, by the amount of space available for stowing the extra beer in ships. The last rum ration was on 31 July 1970 and became known as Black Tot Day as sailors were unhappy about the loss of the rum ration. There were reports that the day involved sailors throwing tots into the sea and the staging of a mock funeral in a training camp. In place of the rum ration, sailors were allowed to buy three one-half imperial pint cans of beer a day and improved recreational facilities. While the rum ration was abolished, the order to "splice the mainbrace", awarding sailors an extra tot of rum for good service, remained as a command which could only be given by the Monarch and is still used to recognise good service. Rum rations are given on special occasions: in recent years, example included the 100th anniversary of the Canadian Royal Navy in 2010 and after the Queen's Diamond Jubilee celebrations in 2012.
In the United States Navy, the daily ration was one-half US pint of distilled spirits until 1842, when it was reduced to one gill. It was abolished in 1862. While the Royal Australian Navy never issued the rum ration, their sailors were entitled to the rum ration when they were on Royal Navy ships until 1921; the Royal Canadian Navy abolished the rum ration in 1972, the last navy to issue the rum ration the Royal New Zealand Navy, abolished the practice on 28 February 1990. Beer day
Webster's Dictionary
Webster's Dictionary is any of the dictionaries edited by Noah Webster in the early nineteenth century, numerous related or unrelated dictionaries that have adopted the Webster's name. "Webster's" has become a genericized trademark in the U. S. for dictionaries of the English language, is used in English dictionary titles. Merriam-Webster is the corporate heir to Noah Webster's original works, which are in the public domain. Noah Webster, the author of the readers and spelling books which dominated the American market at the time, spent decades of research in compiling his dictionaries, his first dictionary, A Compendious Dictionary of the English Language, appeared in 1806. In it, he popularized features which would become a hallmark of American English spelling and included technical terms from the arts and sciences rather than confining his dictionary to literary words. Webster was a proponent of English spelling reform for reasons both nationalistic. In A Companion to the American Revolution, John Algeo notes: "it is assumed that characteristically American spellings were invented by Noah Webster.
He was influential in popularizing certain spellings in America, but he did not originate them. Rather he chose existing options such as center and check on such grounds as simplicity, analogy or etymology". In William Shakespeare's first folios, for example, spellings such as center and color are the most common, he spent the next two decades working to expand his dictionary. In 1828, at the age of 70, Noah Webster published his American Dictionary of the English Language in two quarto volumes containing 70,000 entries, as against the 58,000 of any previous dictionary. There were 2,500 copies printed, at $20 for the two volumes. At first the set sold poorly; when he lowered the price to $15, its sales improved, by 1836 that edition was exhausted. Not all copies were bound at the same time. In 1841, 82-year-old Noah Webster published a second edition of his lexicographical masterpiece with the help of his son, William G. Webster, its title page does not claim the status of second edition noting that this new edition was the "first edition in octavo" in contrast to the quarto format of the first edition of 1828.
Again in two volumes, the title page proclaimed that the Dictionary contained "the whole vocabulary of the quarto, with corrections and several thousand additional words: to, prefixed an introductory dissertation on the origin and connection of the languages of western Asia and Europe, with an explanation of the principles on which languages are formed. B. L. Hamlen of New Haven, prepared the 1841 printing of the second edition; when Webster died, his heirs sold unbound sheets of his 1841 revision American Dictionary of the English Language to the firm of J. S. & C. Adams of Amherst, Massachusetts; this firm bound and published a small number of copies in 1844 – the same edition that Emily Dickinson used as a tool for her poetic composition. However, a $15 price tag on the book made it too expensive to sell so the Amherst firm decided to sell out. Merriam acquired rights from Adams, as well as signing a contract with Webster’s heirs for sole rights; the third printing of the second edition was by George and Charles Merriam of Springfield, Massachusetts, in 1845.
This was the first Webster's Dictionary with a Merriam imprint. Lepore demonstrates Webster's innovative ideas about language and politics and shows why Webster's endeavours were at first so poorly received. Culturally conservative Federalists denounced the work as radical—too inclusive in its lexicon and bordering on vulgar. Meanwhile, Webster's old foes, the Jeffersonian Republicans, attacked the man, labelling him mad for such an undertaking. Scholars have long seen Webster's 1844 dictionary to be an important resource for reading poet Emily Dickinson's life and work. One biographer said, "The dictionary was no mere reference book to her, he shows the ways in which American poetry has inherited Webster and drawn upon his lexicography in order to reinvent it. Austin explicates key definitions from both the Compendious and American dictionaries and brings into its discourse a range of concerns including the politics of American English, the question of national identity and culture in the early moments of American independence, the poetics of citation and of definition.
Webster's dictionaries were a redefinition of Americanism within the context of an emergent and unstable American socio-political and cultural identity. Webster's identification of his project as a "federal language" shows his competing impulses towards regularity and innovation in historical terms; the contradictions of Webster's project represented a part of a larger dialectical play between liberty and order within Revolutionary and post-Revolutionary political debates. Noah Webster's assistant, chief competitor, Joseph Emerson Worcester, Webster's son-in-law Chauncey A. Goodrich, published an abridgment of Noah Webster's 1828 American Dictionary of the English Language in 1829, with the same number of words and Webster's full definitions, but with truncated literary references and expanded etymology. Although it was more successful f
Wine
Wine is an alcoholic drink made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol, carbon dioxide, heat. Different varieties of grapes and strains of yeasts produce different styles of wine; these variations result from the complex interactions between the biochemical development of the grape, the reactions involved in fermentation, the terroir, the production process. Many countries enact legal appellations intended to define qualities of wine; these restrict the geographical origin and permitted varieties of grapes, as well as other aspects of wine production. Wines not made from grapes include rice wine and fruit wines such as plum, pomegranate and elderberry. Wine has been produced for thousands of years; the earliest known traces of wine are from Georgia and Sicily although there is evidence of a similar alcoholic drink being consumed earlier in China. The earliest known winery is the 6,100-year-old Areni-1 winery in Armenia. Wine reached the Balkans by 4500 BC and was consumed and celebrated in ancient Greece and Rome.
Throughout history, wine has been consumed for its intoxicating effects. Wine has long played an important role in religion. Red wine was associated with blood by the ancient Egyptians and was used by both the Greek cult of Dionysus and the Romans in their Bacchanalia; the earliest archaeological and archaeobotanical evidence for grape wine and viniculture, dating to 6000–5800 BC was found on the territory of modern Georgia. Both archaeological and genetic evidence suggest that the earliest production of wine elsewhere was later having taken place in the Southern Caucasus, or the West Asian region between Eastern Turkey, northern Iran; the earliest evidence of a grape-based fermented drink was found in China, Georgia from 6000 BC, Iran from 5000 BC, Sicily from 4000 BC. The earliest evidence of a wine production facility is the Areni-1 winery in Armenia and is at least 6100 years old. A 2003 report by archaeologists indicates a possibility that grapes were mixed with rice to produce mixed fermented drinks in China in the early years of the seventh millennium BC.
Pottery jars from the Neolithic site of Jiahu, contained traces of tartaric acid and other organic compounds found in wine. However, other fruits indigenous to the region, such as hawthorn, cannot be ruled out. If these drinks, which seem to be the precursors of rice wine, included grapes rather than other fruits, they would have been any of the several dozen indigenous wild species in China, rather than Vitis vinifera, introduced there 6000 years later; the spread of wine culture westwards was most due to the Phoenicians who spread outward from a base of city-states along the Mediterranean coast of what are today Syria, Lebanon and Palestine. The wines of Byblos were exported to Egypt during the Old Kingdom and throughout the Mediterranean. Evidence includes two Phoenician shipwrecks from 750 BC discovered by Robert Ballard, whose cargo of wine was still intact; as the first great traders in wine, the Phoenicians seem to have protected it from oxidation with a layer of olive oil, followed by a seal of pinewood and resin, similar to retsina.
Although the nuragic Sardinians consumed wine before the arrival of the Phoenicians The earliest remains of Apadana Palace in Persepolis dating back to 515 BC include carvings depicting soldiers from Achaemenid Empire subject nations bringing gifts to the Achaemenid king, among them Armenians bringing their famous wine. Literary references to wine are abundant in Homer and others. In ancient Egypt, six of 36 wine amphoras were found in the tomb of King Tutankhamun bearing the name "Kha'y", a royal chief vintner. Five of these amphoras were designated as originating from the king's personal estate, with the sixth from the estate of the royal house of Aten. Traces of wine have been found in central Asian Xinjiang in modern-day China, dating from the second and first millennia BC; the first known mention of grape-based wines in India is from the late 4th-century BC writings of Chanakya, the chief minister of Emperor Chandragupta Maurya. In his writings, Chanakya condemns the use of alcohol while chronicling the emperor and his court's frequent indulgence of a style of wine known as madhu.
The ancient Romans planted vineyards near garrison towns so wine could be produced locally rather than shipped over long distances. Some of these areas are now world-renowned for wine production; the Romans discovered that burning sulfur candles inside empty wine vessels kept them fresh and free from a vinegar smell. In medieval Europe, the Roman Catholic Church supported wine because the clergy required it for the Mass. Monks in France made wine for years. An old English recipe that survived in various forms until the 19th century calls for refining white wine from bastard—bad or tainted bastardo wine; the English word "wine" comes from the Proto-Germanic *winam, an early borrowing from the Latin vinum, "wine" or " vine", itself derived from the Proto-Indo-European stem *win-o-. The earliest attested terms referring to wine are the Mycenaean Greek me-tu-wo ne-wo, meaning "in" or " of the new wine", wo-no-wa-ti-si, meaning "wine garden", written in Linear B inscriptions. Linear B includes, inter alia, an ideogram for wine
Evaporator (marine)
An evaporator, distiller or distilling apparatus is a piece of ship's equipment used to produce fresh drinking water from sea water by distillation. As fresh water is bulky, may spoil in storage, is an essential supply for any long voyage, the ability to produce more in mid-ocean is important for any ship. Although distillers are associated with steam ships, their use pre-dates this. Cook's Pacific exploration ship HMS Resolution of 1771 carried a distiller and Nelson's HMS Victory of 1805 was fitted with distilling apparatus in her galley. Distilling apparatus was only fitted to larger warships and some exploratory ships at this time: a warship's large crew needed more water and they could ill afford the space to carry enough. Cargo ships, their smaller crews carried their supplies with them. With the development of the marine steam engine, their boilers required a continual supply of feedwater. Early boilers used seawater directly. For efficiency, as well as conserving feedwater, marine engines have been condensing engines.
By 1865, the use of an improved surface condenser permitted the use of fresh water feed, as the additional feedwater now required was only the small amount required to make up for losses, rather than the total passed through the boiler. Despite this, a large warship could still require up to 100 tons of fresh water makeup to the feedwater system per day, when under full power. Attention was paid to de-aereating feedwater, to further reduce boiler corrosion; the distillation system for boiler feedwater at this time was termed an evaporator to distinguish it from a separate system or distiller used for drinking water. Separate systems were used in early systems, owing to the problem of contamination from oily lubricants in the feedwater system and because of the different capacities required in larger ships. In time, the two functions became combined and the two terms were applied to the separate components of the system; the first water supply by distillation of boiler steam appeared on early paddle steamers and used a simple iron box in the paddle boxes, cooled by water splash.
A steam supply direct from the boiler, avoiding its lubricants, was led to them. With the development of steam heating jackets around the cylinders of engines such as the trunk engine, the exhaust from this source, again unlubricated, could be condensed; the first distilling plants that boiled a separate water supply from that of the main boiler, appeared around 1867. These were not directly heated by a flame, but had a primary steam circuit using main boiler steam through coils within a steam drum or evaporator; the distillate from this vessel passed to an adjacent vessel, the distilling condenser. As these evaporators used a'clean' seawater supply directly, rather than contaminated water from the boiler circuit, they could be used to supply both feedwater and drinking water; these double distillers appeared around 1884. For security against failure, ships except the smallest were fitted with two sets. Evaporators consume a great deal of steam, thus fuel, in relation to the quantity of fresh water produced.
Their efficiency is improved by working them at a partial vacuum, supplied by the main engine condensers. On modern diesel-powered ships, this vacuum can instead be produced by an ejector worked by the output from the brine pump. Working under vacuum reduces the temperature required to boil seawater and thus permits evaporators to be used with lower-temperature waste heat from the diesel cooling system. One of the greatest operational problems with an evaporator is the build-up of scale, its design is tailored to reduce this, to make its cleaning as effective as possible. The usual design, as developed by Weir and the Admiralty, is for a vertical cylindrical drum, heated by steam-carrying drowned coils in the lower portion; as they are submerged, they avoid the most active region for the deposition of scale, around the waterline. Each coil consists of two spirals in a flat plane; each coil is removed for cleaning, being fastened by individual pipe unions through the side of the evaporator. A large door is provided, allowing the coils to be removed or replaced.
Cleaning may be carried with a manual scaling hammer. This has a risk of mechanical damage to the tubes, as the slightest pitting tends to act as a nucleus for scale or corrosion, it is common practice to break light scaling free by thermal shock, by passing steam through the coils without cooling water present or by heating the coils introducing cold seawater. In 1957, the trials ship HMS Cumberland, an obsolete heavy cruiser, was used for the first tests of the'flexing element' distiller, where non-rigid heating coils flexed continually in service and so broke the scale free as soon as it formed a stiff layer. Despite the obvious salinity of seawater, salt is not a problem for deposition until it reaches the saturation concentration; as this is around seven times that of seawater and evaporators are only operated to a concentration of two and a half times, this is not a problem in service. A greater problem for scaling is the deposition of calcium sulphate; the saturation point for this compound decreases with temperature above 60 °C, so that beginning from around 90 °C a hard and tenacious deposit is formed.
To further control scale formation, equipment may be provided to automatically inject a weak citric acid solution into the seawater feed. The ratio is 1:1350, by weight of seawater. Operation of an evaporator represents a costly consumption of main boiler steam, thus fuel. Evaporators for a warship must be adequate to supply the boilers at continuous full powe
