The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a counterbalancing purpose, as well; as the laying down of the keel is the initial step in the construction of a ship, in British and American shipbuilding traditions the construction is dated from this event. The word "keel" comes from Old English cēol, Old Norse kjóll, = "ship" or "keel", it has the distinction of being regarded by some scholars as the first word in the English language recorded in writing, having been recorded by Gildas in his 6th century Latin work De Excidio et Conquestu Britanniae, under the spelling cyulae. Carina is the origin of the term careen. An example of this use is Careening Cove, a suburb of Sydney, where careening was carried out in early colonial days. A structural keel is the bottom-most structural member; the keel runs from the bow to the stern. The keel is the first part of a ship's hull to be constructed, laying the keel, or placing the keel in the cradle in which the ship will be built may mark the start time of its construction.

Large, modern ships are now built in a series of pre-fabricated, complete hull sections rather than being built around a single keel, so shipbuilding process commences with cutting the first sheet of steel. The most common type of keel is the "flat plate keel", this is fitted in the majority of ocean-going ships and other vessels. A form of keel found on smaller vessels is the "bar keel", which may be fitted in trawlers and smaller ferries. Where grounding is possible, this type of keel is suitable with its massive scantlings, but there is always a problem of the increased draft with no additional cargo capacity. If a double bottom is fitted, the keel is inevitably of the flat plate type, bar keels being associated with open floors, where the plate keel may be fitted. Hydrodynamic keels have the primary purpose of interacting with the water and are typical of certain sailboats. Fixed hydrodynamic keels have the structural strength to support the weight of the boat. In sailboats, keels serve two purposes: 1) as an underwater foil to minimize the lateral motion of the vessel under sail and 2) as a counterweight to the lateral force of the wind on the sail that causes rolling to the side.

As an underwater foil, a keel uses the forward motion of the boat to generate lift to counteract the leeward force of the wind. Related foils include centerboards and daggerboards, which do not have the secondary purpose of being a counterweight; as counterweight, a keel offsets the heeling moment with increasing angle of heel. Moveable sailboat keels may pivot, retract upwards, or swing sideways in the water to move the ballasting effect to one side and allow the boat to sail in a more upright position. Coin ceremony Kelson False keel Daggerboard Leeboard Bilgeboard Bruce foil Keelhauling – an archaic maritime punishment Rousmaniere, The Annapolis Book of Seamanship, Simon & Schuster, 1999 Chapman Book of Piloting, Hearst Corporation, 1999 Herreshoff, The Sailor’s Handbook, Little Brown and Company Seidman, The Complete Sailor, International Marine, 1995 Jobson, Sailing Fundamentals, Simon & Schuster, 1987

The Bethlehem Waterworks known as the Old Waterworks or 1762 Waterworks, is believed to be the oldest pump-powered public water supply in what is now the United States. The pumphouse, which includes original and replica equipment, is located in the Colonial Industrial Quarter of downtown Bethlehem, between the Monocacy Creek and Main Street, it was declared an American Civil Engineering Landmark in 1971, an American Water Landmark in 1971, a National Historic Landmark in 1981. The building is a contributing property to the Historic Moravian Bethlehem Historic District, designated as a National Historic Landmark District in 2012 and named to the U. S. Tentative List in 2016 for nomination to the World Heritage List; the first Waterworks within Bethlehem was designed and built by millwright Hans Chistoph Christensen from Denmark in 1755 to more efficiently bring water from the spring at the bottom of the hill to the top of the hill where most of the living quarters could be found. This spring provided a flow of eight hundred gallons per minute, enough to provide water for drinking and bathing, as well as water in case of fire.

The first building was a wooden structure designed by Hans and described by Robert Rau "the machinery was placed in a frame building, 19 by 22, a few yards east of the oil and bark mill, whither the spring water was led by a conduit into a cistern. The pump was made of the cylinder being five inches in diameter; the water was forced through wooden pipes up the hill into a wooden reservoir or distributing tank built within the little square. The pipes were bored hemlock logs, floated down the Lehigh River from Gnadenhuetten on the Mahoning." Persistent issues with leaking and bursting pipes kept this first structure from being completed, despite switching from wood to lead pipes. Growing demand for water and a more efficient system required enlargement of the plant, as well as more powerful machinery. Hans built the limestone Waterworks in 1762 to meet these needs and received thirty shillings in payment for his work; the limestone Waterworks building is located in the floodplain of Monocacy Creek in the Colonial Industrial Quarter, an important part of the historic district of Bethlehem.

It is a 2-1/2 story building, built out of limestone rubble, about 24 feet square and covered by a red tile roof. It is set over an otherwise open holding pit, fed by a wood-lined trench from a nearby spring. There are doors on three sides, one of, at a higher elevation owing to the sloping terrain; the machinery includes a replica waterwheel, reproduced from the original master craftsman's drawings which were preserved. In colonial Bethlehem, water power replaced human and horse power; the wheel was turned by water supplied from the creek and provided the power needed to move water up to the settlement above. The power generated by one water wheel was the equivalent of 100 men and an undershot waterwheel powered three cast-iron pumps, forcing the water through pipes into a collecting tower located nearly 94 feet uphill where Central Moravian Church stands today. From the tower, gravity carried the water into five separate cisterns on the hillside to be used by the various Choir houses. Hans' system was imperfect, with overpressure bursting other problems.

Conflict arose when the city’s growth continued but the power supplied by Monocacy Creek could not match. Both the Waterworks and the Oil Mill used the same tail race to supply the power for their needs and by the early 1800s the Oil Mill had to halt productivity for two days out of the week so the Waterworks could fill the town’s reservoirs; the Waterworks operations were relocated to the Oil Mill building in 1832 due to an increase on water demands from the town that the 1762 Waterworks could not meet. The Oil Mill operated as the new Waterworks for 81 years, serving the continually growing community well into the early twentieth century. Water quality from the spring soon became a major issue with epidemics of typhoid and dysentery being traced to the water supply and, under order of the Pennsylvania Commissioner of Health, the waterworks operations were shut down permanently in January of 1913; the system is believed to be the first pump-powered water supply to be implemented in what is now the United States.

The town of Boston, Massachusetts had a municipal water supply as early as 1652, but it was purely powered by gravity. This European style of technology for municipal water distribution was not matched in America until the Philadelphia water system was completed in 1801. Archaeological studies were conducted at the Waterworks site in 1964 and 1972. In 1972 the building, the waterwheel, the pumping mechanism were restored using the original 18th century master craftsmen’s drawing in the collection of the Moravian Archives. In 2004 the waterwheel sustained damage from Hurricane Ivan, through a Save America's Treasures Grant was restored in 2009 using those same drawings. Sections of the original wooden pipes used by the Waterworks are on display at the Moravian Museum of Bethlehem; the 1762 Waterworks is owned by the city of Bethlehem with a long-term lease to Historic Bethlehem Inc. a member institution of Historic Bethlehem Museums & Sites, a 5013 non-profit organization. The history of the 1762 Waterworks is interpreted today on guided tours.

The building is presently closed to the public. List of National Historic Landmarks in Pennsylvania National Register of Historic Places listings in Northampton County

Unabomber for President was a political campaign with the overt aim of electing "The Unabomber" as a write-in candidate in the 1996 presidential election, despite the fact that he was not allowed to serve. The campaign's slogan was the Shermanesque statement "if elected, he will not serve." The campaign was launched in Boston in September 1995 by Lydia Eccles – a Boston artist who had long harbored concerns about "totalitarian tendencies in technology" – and antinatalist Chris Korda. It took the overt form of Unabomber Political Action Committee. Influenced by ideas of the Situationist International, the group included anarchists, hardcore punks, 1960s counter-culturalists, eco-socialists, pacifists and primitivists, its supporters included decentralized anarchist collective CrimethInc. and the Church of Euthanasia. The campaign received national publicity, attempts by news organizations to portray it as frivolous were resisted by UNAPACK, who insisted that the issues raised by Kaczynski were portentous, concerning "the fate of mankind".

In the words of the Phoenix New Times, the campaign was "an effort designed to cast votes in protest of the existing hierarchy and its potential replacement." The Maoist Internationalist Movement criticized the campaign as typifying "life-style politics anarchism" and as encouraging protest votes instead of seizing political power from the upper class. As Bill Brown, director of the campaign's New York City office, said at the time: "Most of the media are unable to deal with the campaign…here is no way for people to understand why you would say'Unabomber for President' and that gives us a tactical opportunity to explain ourselves." The intended symbolism of the campaign was not that it was a joke, but that the political system was a joke. The campaign won Reason magazine's worst bumper sticker for their effort "FED UP WITH'PROGRESS'? Write-in UNABOMBER For PRESIDENT'96." UNAPACK's web site. UNAPACK's press page Unabomber for President Political Action Committee, New York City Office Nomination for Unabomber for President radio segment from September 9, 1996 by Democracy Now!

Top Ten Reasons to Vote Unabomber, by Lydia Eccles