Terminology, Equipment & Inventions
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Beacon // n.
1 a fire or light set up in a high or prominent position as a warning etc. b Brit. (now often in place names) a hill suitable for this.
2 a visible warning or guiding point or device (e.g. a lighthouse, navigation buoy, etc.).
3 a radio transmitter whose signal helps fix the position of a ship or aircraft.
4 Brit. = Belisha beacon.
[Old English beacn, from West Germanic]
A beacon was never looked upon as a formal sea mark nor does it refer to a lighthouse. Originally this term referred to a fire beacon. In England during the 5th century numerous fire beacons were established from Cornwall to London. If an invasion was possible one of these beacons would be lit. When spotted all of the other beacons would be set ablaze. In terms of time from the lighting of the first beacon, a warning could be in London within two hours from the tip of Cornwall more than 400 miles away.
This was proved during the attempted Spanish Armada during the reign of Elizabeth I in the 16th century.
Landmark // n.
1 a conspicuous object in a district etc. b an object marking the boundary of an estate, country, etc.
2 an event, change, etc. marking a stage or turning point in history etc.
Lighthouse // n.
a tower or other structure containing a beacon light to warn or guide ships at sea.
Seamark is a prominent feature that is readily recognised by anyone on board a ship at sea.
They have always been considered to be more important than lights in the broadest sense. This because seamarks were clumps of trees, a church spire, rock formations and other land fall sights.
With the advent of lights, beacons and buoys these later took on the more familiar description for a seamark.
Other nations use different terms.The Germans refer to a 'leuchtturme' or light tower; the Spanish and Italians use 'phare', with English speaking peoples calling them lighthouses.
However, during the early days of the Lloyd's signalling stations, the lexicographers argued in vain that their towers were the only true lighthouses.
But when considering either 'pharos' or 'lighthouses', they are in fact the same, because the word pharology means the study of things related to lighthouses.
Argand burner, an efficient type of oil lamp, patented in 1784 in Britain by Aime Argand, a Swiss. Air is admitted via a metal tube to the inside of a cylindrical wick: a glass chimney further increases the air supply. The wick provides a large contact area between the flame and the fuel, while the air supply ensures complete combustion. The principle of the Argand lamp was later applied to gas lighting.
Dealings in ballast were two fold. Firstly the dredging up of sand and shingle from the river bed to keep the channels and wharfages clear and secondly the supplying of gravel to ships, for steading them when light or unladen.
Originally ballastage was officially 'gravel, sand soil of the Thames' which the operator was to 'land and lay on shore upon any of our waste ground;' it was also forbidden to 'sell, vend, give or utter any gravel, sand or soil without a license.'
These licences were held by recognised ballast owners although in reality they were only sub-contractors. The only way that the vessels in the Thames; His Majesty's as well as others, could obtain their shingle or gravel was through these owners. Therefore the most profitable way was to make the ballastage a monopoly.
Ballastage became one of the first monopolies in the British Isles, which was given as a Royal Patent and privilege to the Lord High Admirals of England. In turn these Lords sub-let the rights of ballastage, with the first Patent being issued to the Earl of Surrey in 1517.
(example Bishop Rock, Round Island)
This unit comprised of one lens assembly above the other, with each tier having 5 sets of 2 panels, with a 1330 mm focus. Inturn this complete assembly rotated to produce a double flash every minute.
Its light source had to be very wide, in order to provide an appreciable length of flash that could be readily seen by the distant viewer, with the whole apparatus only rotating once in 300 seconds.
An oil burner with 8 concentric wicks was required for each tier of the lenses.
Heat generated by these massive burners is alleged to to be hot enough for the keepers to fry up their eggs and bacon, prior to the lioght being extinguished.
catoptric // adj.
of or relating to a mirror, a reflector, or reflection.
E.G. A car headlamp normal has a catoptric reflector behind the light source. The glass in front of the light source is classed as dioptric because it has small prisms which refract the beam in a specific direction.
as pertaining to optical prisms ( a. kat-a-di-op-trik,) reflecting and refracting of light. In lighthouses the prisms not only refract the illumination into a horizontal beam, but they also have reflecting surfaces which capture any errant rays of light and re-direct them through the refracting portion of the prisms. This results in a more concentrated beam of light and also requires a much smaller light source.
coal-gas, a valuable product of the manufacture of coke from coal, containing largely hydrogen and methane, plus carbon oxides, ethene, and other gases. Coal-gas was used for gas lighting and for heating in Europe for over 150 years. It was replaced in the 1970s by natural gas from the North Sea or from petroleum feedstocks. The presence in coal gas of carbon monoxide (which is absent in natural gas) makes it extremely toxic.
coke, the solid residue left when coal is heated in the absence of air, or in a limited supply (carbonization). There is a limited domestic and industrial market for coke, and it is used primarily as a fuel or as a reducing agent in the iron and steel industry, most of it in blast-furnaces. By-products of the coking process include coal-gas and coal-tar. Darby was the first to use coke successfully for iron smelting early in the 18th century, an innovation which paved the way for the Industrial Revolution. Next to combustion, carbonization is the largest application of coal. A small amount of coke is also made from other feedstocks. Petroleum refinery residues, for example, yield a coke used to make arc-steel electrodes and anodes for aluminium smelting.
dioptric // adj. Optics
1 serving as a medium for sight; assisting sight by refraction (dioptric glass; dioptric lens).
2 of refraction; refractive.
[Greek dioptrikos from dioptra, a kind of theodolite]
helical /, / adj.
having the form of a helix.
helicoid adj. & n.
helix // n. (pl. helices /, /)
1 a spiral curve (like a corkscrew) or a coiled curve (like a watch spring).
2 Geom. a curve that cuts a line on a solid cone or cylinder, at a constant angle with the axis.
3 Archit. a spiral ornament.
4 Anat. the rim of the external ear.
[Latin helix -icis from Greek helix -ikos]
a. hol-o-fo-tal, reflecting all the light unbroken. (Gr.holos, and phos, light.)
Incandescent Oil Burner
Keeper lighting a Hood burner inside of the Bishop Rock lighthouse. Photo by Frank Gibson.
incandescent // adj.
1 glowing with heat.
2 shining brightly.
3 (of an electric or other light) produced by a glowing white-hot filament.
[French from Latin incandescere (as in-2, candescere, inceptive of candere ‘be white’)]
The principle of this mineral oil burner was the turning of pressurized paraffin into a gas. The method used was to activate a heater below a retort containing the vaporized oil, until a white fuming gas seeped through a silk mantle. It was then ignited by using a lit taper by a keeper. The resulting illumination was extremely bright.
David Hood's adaption of the basic incandescent burner also included an auto-form mantle. This unit would expand to nearly twice its size when hot and could withstand a greater gas pressure. When cold it shrank back to its original size. However the homogenous illumination effectively reduced the oil consumption by a third.
Lighting, the production of illumination by artificial means. All forms of lighting used up to 100 years ago depended on the combustion of either solid or liquid fuels. Mesopotamian oil lamps date from 8000 BC, and candles were first used in ancient Egypt. In the Middle Ages, pedestrians carried a flambeau--a torch of twisted fibres coated with a flammable material.
The next major advance was the Argand lamp, with a tubular wick and glass chimney, which gave a brighter, steadier light. Oil lamps were improved steadily until the beginning of the 20th century. The paraffin lamp was extensively used in rural districts.
Gas lighting was in common use in urban areas by the mid-19th century in houses, factories, and for street-lighting.
Around 1870 the incandescent electric lamp was invented independently by Swan and Edison, heralding the beginning of the modern lighting era. The electricity generation and supply industry initially arose to supply power for electric lighting.
The development of tungsten filaments in the early 1900s was an important advance, allowing lamps to run at a higher temperature and therefore emit more and whiter light for the same electrical input.
The neon light was developed during the late 19th century, and was used for decoration and advertising.
Other gas-discharge lamps using mercury and sodium were used for street-lighting; xenon discharge tubes are used in lighthouses.
In the 1930s the fluorescent lamp was developed; this is very efficient for lighting interiors. More recent developments include microscopic filament lamps, enabling surgeons to examine the internal cavities of a patient's body (endoscopy).
the period of illumination longer than the period of eclipse
(+) Oil lamps
oil lamp, a lamp that produces light by the combustion of oil. Prehistoric oil lamps consisted of a flat stone with a hollow full of animal oil which burned at a moss wick. By 500-400 BC, clay, copper, and bronze oil lamps had come into general use. These burned vegetable oil at a vegetable-fibre wick. Lamps using mineral oil were introduced in about AD 50, and in 1490 Leonardo da Vinci designed a light with a glass chimney, though this was not widely adopted. A great advance was made in 1784 when Aime Argand of Switzerland patented the Argand lamp, which burned more brightly and steadily. In 1885 highly efficient pressure lamps were introduced, which burned vaporized paraffin oil to heat a gas-mantle to incandescence.
pharos // n.
a lighthouse or a beacon to guide sailors.
[Latin from Greek Pharos, the name of an island off Alexandria where a famous lighthouse stood]
The first planned lighthouse is understood to be the majestic Pharos of Alexandria established around 285 B.C.
Other historian dispute this claim by stating they believe this should be the Colossus of Rhodes erected in 300 B.C.
The origins of the Pharos was well documented. According to the Geographia Nubiensis, the Pharos was '100 statues of man, or 300 cubits, or 512 English feet (156 m)'.
The name of this lighthouse was derived from the small island on which it stood.
theodolite // n.
a surveying instrument for measuring horizontal and vertical angles with a rotating telescope.
theodolitic // adj.
[16th c.: modern Latin theodelitus, of unknown origin]