Watercraft known as water vessels or waterborne vessels, are vehicles used in water, including ships, boats and submarines. Watercraft have a propulsive capability and hence are distinct from a simple device that floats, such as a log raft. Most watercraft would be described as either a boat. However, there are numerous craft which many people would consider neither a ship nor a boat, such as: surfboards, underwater robots and torpedoes. Although ships are larger than boats, the distinction between those two categories is not one of size per se. Ships are large ocean-going vessels. A rule of thumb says "a boat can fit on a ship, but a ship can't fit on a boat", a ship has sufficient size to carry its own boats, such as lifeboats, dinghies, or runabouts. Local law and regulation may define the exact size. Traditionally, submarines were called "boats" reflecting their cramped conditions: small size reduces the need for power, thus the need to surface or snorkel for a supply of the air that running marine diesel engines requires.

A merchant ship is any floating craft. In this context, a passenger ship's "cargo" is its passengers; the term "watercraft" is used to describe any individual object: rather the term serves to unify the category that ranges from jet skis to aircraft carriers. Such a vessel may be used in freshwater; the purposes behind watercraft designs and skills are for seafaring education or leisure activities and resource extraction, transportation of cargo or passengers, for conducting combat or salvage operations. In general, the purpose of a water vehicle identifies its utility with a maritime industry sub-sector; the design from which a water vehicle is created seeks to achieve a balance between internal capacity and seaworthiness. Tonnage is predominantly a consideration in transport operations, speed is important for warships, safety is a primary consideration for less experienced or smaller and less stable training and leisure vehicles; this is due to the great level of regulatory compliance required by the larger watercraft, which ensures infrequent instances of foundering at sea through application of extensive computer modeling and ship model basin testing before shipyard construction begins.

Water vehicles have been propelled by people with poles, paddles, or oars, through manipulation of sails that propel by wind pressure and/or lift, a variety of engineered machinery that create subsurface thrust through the process of internal combustion or electricity. The technological history of watercraft in European history can be divided by reference to marine propulsion as simple paddle craft, oared galleys from the 8th century BCE until the 15th century, lateen sail during the Age of Discovery from the early 15th century and into the early 17th century, full rigged ships of the Age of Sail from the 16th to the mid 19th century, the Age of Steam reciprocating marine steam engine between 1770 and 1914, the steam turbine gas turbine, internal combustion engines using diesel fuel, petrol and LNG as fuels from the turn of the 20th century, which have been supplemented to a degree by nuclear marine propulsion since the 1950s in some naval watercraft. Current technological development seeks to identify cheaper and less polluting sources of propulsion for watercraft of all shapes and sizes.

Secondary applications of technology in watercraft have been those of used structural materials, navigation aids. The purpose of usage and the physical environment define the materials used in construction which had included grasses, timbers, metals combined with timber or without and plastic derivatives, others. Watercraft registration is the registration of a watercraft with a government authority. In the United States, it consists of an alphanumeric string called a vessel registration number, issued by the state's Department of Motor Vehicles. Navigation aids have varied over time: from astronomical observation, to mechanical mechanisms, more analogue and digital computer devices that now rely on GPS systems. Naval weapon systems have followed the development in land weapons, developing from: aircraft carriers breech-loading rifled guns direct enemy hull ramming to use of basic mechanical projectiles firing shells missiles and remotely piloted devices naval mine layers and minesweeper smooth-bore cannonball firing guns torpedo-armed submarines warships armed with fire control directed weaponsUntil development of steam propulsion was coupled with rapid-firing breech-loading guns, naval combat was concluded by a boarding combat between the opposing crews.

Since the early 20th century, there has been a substantial development in technologies which allow force projection from a naval task force to a land objective using marine infantry. The Canadian Museum of Civilization - Native Watercraft in Canada A History of Recreational Small Watercraft Recreational Watercraft

The Mirror Crack'd from Side to Side

The Mirror Crack'd from Side to Side is a work of detective fiction by Agatha Christie and first published in the UK by the Collins Crime Club on 12 November 1962 and in the US by Dodd and Company in September 1963 under the shorter title of The Mirror Crack'd and with a copyright date of 1962. The UK edition retailed at fifteen shillings and the US edition at $3.75. It features Miss Marple, it was dedicated by Christie: "To Margaret Rutherford, in admiration." The novel received good reviews on publication, for "the shrewd exposition of what makes a female film star tick", being easy to read, though the plot was not as "taut" as some of Christie's novels. A review found it "one of the best of her books" and liked the way that "the changes in village life and class structure since the war are detailed". While recovering from an illness, Jane Marple takes a fall, she encounters Heather Badcock, who brings her to her home and relates a story of meeting American actress Marina Gregg, who has moved to England to star in a film about Elisabeth of Austria and purchased Gossington Hall from Marple's friend Dolly Bantry.

Gregg and her latest husband, producer Jason Rudd, host a fête at Gossington Hall in honor of St John Ambulance. Among the guests in attendance are Mrs Bantry, actress Lola Brewster, Gregg's personal friend Ardwyck Fenn, Heather Badcock and her husband Arthur. All five are invited to a private room to have their picture taken. Upon meeting Gregg, Heather shares the story of meeting her in Bermuda and receiving her autograph, during which Mrs Bantry notices a strange look cross Gregg's face. Mrs Bantry takes several other women to see the renovations made to the house only to be interrupted upon discovering Heather has collapsed without explanation. Despite all attempts to revive her, Heather is pronounced dead. Mrs. Bantry informs Marple about the events surrounding the fête and the frozen look on Marina's face, comparing it to a phrase from Alfred, Lord Tennyson's poem The Lady of Shalott. Detective-Inspector Dermot Craddock spearheads the investigation, learning that Heather died as a result of ingesting six times the recommended dose of the tranquilizer Calmo.

The drug had been slipped into a daiquiri that belonged to Gregg but was offered to Heather after someone jogged her arm and caused her to spill it. Operating on the assumption that Gregg was the intended target, Craddock proceeds to delve into her complicated past. Desperate to have a child of her own, she was unable to conceive, she adopted three children but became pregnant and gave birth to a mentally disabled son before suffering a nervous breakdown. One of the children, Margot Bence, is revealed to have been present at Gossington Hall on the day of the fête but she denies killing Gregg despite her hatred towards her adoptive mother; as the investigation continues, two more people are killed over the course of twenty-four hours. Rudd's social secretary, Ella Zielinsky, dies first from cyanide poisoning after the atomizer she uses for her hay fever is tainted with prussic acid; that night, Gregg's butler, Giuseppe, is shot twice in the back in his bedroom after spending the day in London and depositing £500 into his bank account.

Ardwyck Fenn informs Craddock he received a phone call several days before, accusing him of killing Heather, he recognized the anonymous caller as Ella when she sneezed. Marple's house cleaner, Cherry Baker, reveals her friend Gladys, a server at Gossington Hall on the day of the fête, told her she believes Heather deliberately spilled the cocktail and that she was going to meet Giuseppe before he died. After sending Gladys on a vacation to Bournemouth and phoning the vicar, she travels to Gossington Hall only to discover Gregg died in her sleep from an overdose. With Craddock and Rudd present, Marple reconstructs the moment when Heather recounted the story of her meeting Gregg in Bermuda revealing that Gregg was the murderer all along. Heather, suffering from German measles at the time, was indirectly responsible for Gregg's son being born disabled and for Gregg herself suffering a nervous breakdown. Overcome with rage, Gregg doctored her own daiquiri before making it, she tried to convince everyone the poisoned drink was meant for her and killed Ella and Giuseppe after they deduced she was the killer.

Marple sent Gladys away to protect her from becoming Gregg's next victim. Marple implies Rudd administered the overdose to protect her and to prevent her from taking another life. Rudd neither confirms nor denies her suspicions, instead commenting on his wife's beauty and the suffering she endured; the title of the novel comes from the poem The Lady of Shalott by Lord Tennyson. The Lady of Shalott lives in a tower near Camelot, sees it only reflected in a glass, she will be doomed. This poem is referred to by name several times in the novel, with these lines quoted: Out flew the web and floated wide- The mirror crack'd from side to side. At the end, Miss Marple quotes the last three lines in referring to the dead actress: He said, "She has a lovely face. Miss Marple: Detective of St Mary Mead, recovering from an illness. Mrs Cherry Baker: Young house cleaner for Miss Marple. Jim Baker: Husband of Cherry. Miss Knight: Works as carer for Miss Marple, sent by Miss Marple's nephew Raymond West, while she is r

Backline (stage)

The term backline is used in popular music and sound reinforcement system contexts to refer to electronic audio amplification equipment and speaker enclosures that are placed behind the band or the rhythm section on stage, including amplifiers and speaker cabinets for guitars, bass guitars and keyboards. Such equipment is rented or leased by the band or their management, or provided by the venue. Speakers placed at the front of the stage facing the performers are known as monitor speakers or "foldback." The main speakers facing the audience are sometimes referred to as "front of house." In rock music's early days in the early 1960s, PA systems were not loud or powerful. As a result, 1960s rock bands used the PA system just for the vocals if they were playing at a large venue; as a result, the rhythm section musicians playing electric guitar, electric bass and keyboards were expected to produce enough volume to fill the venue using their own instrument amplifiers. To achieve venue-filling sound with their instruments, bands from the 1960s used large, powerful guitar "stacks" and big speaker enclosures.

A standard cabinet used by bassists during this era was the heavy 8x10 cabinet, which contains eight ten-inch speakers. Guitarists used one or two 4x12 cabinets, referred to as a half stack or stack. During the 1960s, the PA speakers and the band's amplification were all set in a line, which conceptually grouped PA and instrument amplification together; this changed over the 1970s and 1980s, as PA systems became powerful enough to amplify all of the band's instruments and the vocals. During this era, the backline gear was set behind the PA speakers to create the modern audio stage set-up. Modern monitoring techniques, in which monitor speakers pointing at the performers are placed on the stage, as well as the concepts of frontline and backline, developed during this era. Backline equipment can be rented for concert tours. Many travelling musicians prefer not to transport their own gear across borders and continents for fear of damage or customs hassles. In some countries, all electronic and electric gear needs documentation and certification by an electrical expert before it can be brought into the country.

Another issue is that some bands may travel to a country or continent which uses a different type of AC mains power and differently-shaped electric plugs. Festivals and venues provide backline gear because it speeds up the process of changing bands on a stage, because the gear does not have to be moved on and off the stage and soundchecked again. Having professional backline gear means that the sound engineers do not have to deal with modest-quality amps, which may have ground loops, hum or noise, or produce unintended clipping when the amp is pushed to its maximum volume. Top bands may have specific backline requirements, including a list of amplifiers and instruments, but the brand names and model numbers. An emerging group on its first small club tour will not have the negotiating leverage to request specific brands and models of backline gear; as such, an emerging band's backline "technical specifications" request as part of its contract may only ask venue managers for general types of equipment, while a top touring band's contract rider may specify, for example, an Ampeg SVT Pro bass amplifier and 8x10" Ampeg cabinet for the bassist and a Fender Bandmaster amp head and a Fender 4x10" speaker cabinet for the electric guitarist.

Backline guitar technicians, audio technicians and stage crew set up and put away the backline equipment. Backline gear, used will need regular maintenance to ensure that it provides reliable performance. In places where the backline is left in place indefinitely, the gear may be powered down when not in use, a cloth may be placed over top of the equipment so it does not get dusty. In music festivals with outdoor temporary stages, the backline equipment may have to be transported to a locked, climate-controlled storage area at the end of each day, to protect it from theft, vandalism, or inclement weather. Backline techs who travel with touring acts may be called roadies, although the road crew's role is limited to transporting and positioning the instruments and gear. Maintenance and repair of instruments and gear is a specialized task handled by guitar and drum technicians