Polybius was a Greek historian of the Hellenistic period noted for his work The Histories, which covered the period of 264–146 BC in detail. The work describes the rise of the Roman Republic to the status of dominance in the ancient Mediterranean world and includes his eyewitness account of the Sack of Carthage in 146 BC. Polybius is important for his analysis of the mixed constitution or the separation of powers in government, influential on Montesquieu's The Spirit of the Laws and the framers of the United States Constitution. Polybius was born around 200 BC in Megalopolis, when it was an active member of the Achaean League, his father, was a prominent, land-owning politician and member of the governing class who became strategos of the Achaean League. Polybius was able to observe first hand the political and military affairs of Megalopolis, he developed an interest in horse riding and hunting, diversions that commended him to his Roman captors. In 182 BC, he was given quite an honor when he was chosen to carry the funeral urn of Philopoemen, one of the most eminent Achaean politicians of his generation.
In either 169 BC or 170 BC, Polybius was elected hipparchus, an event which presaged election to the annual strategia. His early political career was devoted towards maintaining the independence of Megalopolis. Polybius’ father, was a prominent advocate of neutrality during the Roman war against Perseus of Macedon. Lycortas attracted the suspicion of the Romans, Polybius subsequently was one of the 1,000 Achaean nobles who were transported to Rome as hostages in 167 BC, was detained there for 17 years. In Rome, by virtue of his high culture, Polybius was admitted to the most distinguished houses, in particular to that of Lucius Aemilius Paullus Macedonicus, the conqueror in the Third Macedonian War, who entrusted Polybius with the education of his sons and Scipio Aemilianus. Polybius remained on cordial terms with his former pupil Scipio Aemilianus and was among the members of the Scipionic Circle; when Scipio defeated the Carthaginians in the Third Punic War, Polybius remained his counsellor.
The Achaean hostages were released in 150 BC, Polybius was granted leave to return home, but the next year he went on campaign with Scipio Aemilianus to Africa, was present at the Sack of Carthage in 146, which he described. Following the destruction of Carthage, Polybius journeyed along the Atlantic coast of Africa, as well as Spain. After the destruction of Corinth in the same year, Polybius returned to Greece, making use of his Roman connections to lighten the conditions there. Polybius was charged with the difficult task of organizing the new form of government in the Greek cities, in this office he gained great recognition. In the succeeding years, Polybius resided in Rome, completing his historical work while undertaking long journeys through the Mediterranean countries in the furtherance of his history, in particular with the aim of obtaining firsthand knowledge of historical sites, he interviewed veterans to clarify details of the events he was recording and was given access to archival material.
Little is known of Polybius' life. He wrote about this war in a lost monograph. Polybius returned to Greece in his life, as evidenced by the many existent inscriptions and statues of him there; the last event mentioned in his Histories seems to be the construction of the Via Domitia in southern France in 118 BC, which suggests the writings of Pseudo-Lucian may have some grounding in fact when they state, " fell from his horse while riding up from the country, fell ill as a result and died at the age of eighty-two". Polybius’ Histories cover the period from 264 BC to 146 BC, its main focus is the period from 220 BC to 167 BC, describing Rome's efforts in subduing its arch-enemy and thereby becoming the dominant Mediterranean force. Books I through V of The Histories are the introduction for the years during his lifetime, describing the politics in leading Mediterranean states, including ancient Greece and Egypt, culminating in their ultimate συμπλοκή or interconnectedness. In Book VI, Polybius describes the political and moral institutions that allowed the Romans to succeed.
He describes the Second Punic Wars. Polybius concludes the Romans are the pre-eminent power because they have customs and institutions which promote a deep desire for noble acts, a love of virtue, piety towards parents and elders, a fear of the gods, he chronicled the conflicts between Hannibal and Publius Cornelius Scipio Africanus such as the Battle of Ticinus, the Battle of the Trebia, the Siege of Saguntum, the Battle of Lilybaeum, the Battle of Rhone Crossing. In Book XII, Polybius discusses the worth of Timaeus’ account of the same period of history, he asserts Timaeus' point of view is inaccurate and biased in favor of Rome. Therefore, Polybius's Histories is useful in analyzing the different Hellenistic versions of history and of use as a credible illustration of actual events during the Hellenistic period. In the seventh volume of his Histories, Polybius defines the historian's job as the analysis of documentation, the review of relevant geographical information, political experience.
Polybius held that historians should only chronicle events whose participants the historian was able to interview, was among the first to champion the notion of factual integrity in historical wri
First Punic War
The First Punic War was the first of three wars fought between Ancient Carthage and the Roman Republic, the two great powers of the Western Mediterranean. For 23 years, in the longest continuous conflict and greatest naval war of antiquity, the two powers struggled for supremacy on the Mediterranean island of Sicily and its surrounding waters, in North Africa; the war began in 264 BC with the Roman conquest of the Carthaginian-controlled city of Messina in Sicily, granting Rome a military foothold on the island. The Romans built up a navy to challenge Carthage, the greatest naval power in the Mediterranean, for control over the waters around Sicily. In naval battles and storms, 700 Roman and 500 Carthaginian quinqueremes were lost, along with hundreds of thousands of lives. Command of the sea was lost by both sides repeatedly. A Roman invasion of Carthaginian Africa was destroyed in battle at the Bagradas and the Roman consul Marcus Atilius Regulus was captured by the Carthaginians in 255. In 23 years, the Romans conquered Sicily and drove the Carthaginians to the west end of the island.
After both sides had been brought to a state of near exhaustion, the Romans mobilized their citizenry's private wealth and created a new fleet under consul Gaius Lutatius Catulus. The Carthaginian fleet was destroyed at the Aegates Islands in 241, forcing the cut-off Carthaginian troops on Sicily to give up. A peace treaty was signed in which Carthage was made to pay a heavy indemnity and Rome ejected Carthage from Sicily, annexing the island as a Roman province; the war was followed by a failed revolt against the Carthaginian Empire. The Romans exploited Carthage's weakness to seize the Carthaginian possessions of Sardinia and Corsica in violation of the peace treaty; the unresolved strategic competition between Rome and Carthage would lead to the eruption of the Second Punic War in 218 BC. The series of wars between Rome and Carthage took the name "Punic" from the Latin adjective for Carthaginian, Punicus; this refers to the Carthaginian heritage as Phoenician colonists. A Carthaginian name for the conflicts does not survive in any records.
Rome had emerged as the leading city-state in the Italian Peninsula, a wealthy, expansionist republic with a successful citizen army. Over the past one hundred years, Rome had come into conflict, defeated rivals on the Italian peninsula incorporated them into the Roman political world. First, the Latin League was forcibly dissolved during the Latin War the power of the Samnites was broken during the three prolonged Samnite wars, the Greek cities of Magna Graecia submitted to Roman power at the conclusion of the Pyrrhic War. By the beginning of the First Punic War, the Romans had secured the whole of the Italian peninsula, except Gallia Cisalpina in the Po Valley. Carthage was a republic that dominated the political and economic affairs of the western Mediterranean Sea on the North African coasts and islands, above all, due to its navy, it originated as a Phoenician colony near modern Tunis. Carthage had become a wealthy centre for trade networks extending from Gadir along the coasts of southern Iberia and North Africa, across the Balearic Islands, Corsica and the western half of Sicily, to the ports of the eastern Mediterranean, including Tyre, its mother city, on the shores of the Levant.
At the height of power, just before the First Punic War, Carthage was hostile to foreign ships in the western Mediterranean. North African peoples, such as the Berbers, in the area around Carthage were loosely associated with Carthage. In the midst of the First Punic War, some tribes rebelled against Carthage, opening a second front while the Carthaginians battled the Romans in Sicily. Greek colonists were a major presence in the western Mediterranean, following centuries of colonial settlement and conflicts with Rome over Magna Graecia and with Carthage over places such as Sicily; the rich, strategically influential, well-fortified Greek colony of Syracuse was politically independent of Rome and Carthage. Hostilities of the First Punic War began with developments involving the Romans and Greek colonists in Sicily and southern Italy. In 288 BC, the Mamertines, a group of Italian mercenaries hired by Agathocles of Syracuse, occupied the city of Messana in the north-eastern tip of Sicily, killing all the men and taking the women as their wives.
At the same time, a group of Roman troops made up of Campanian "citizens without the vote" revolted and seized control of Rhegium, lying across the Straits of Messina on the mainland of Italy. In 270 BC, the Romans regained control of Rhegium and punished the survivors of the revolt. In Sicily, the Mamertines ravaged the countryside and collided with the expanding regional empire of the independent city of Syracuse. Hiero II, tyrant of Syracuse, defeated the Mamertines near Mylae on the Longanus River. Following their defeat, the Mamertines appealed to both Carthage for assistance; the Carthaginians acted first, approached Hiero to take no further action and convinced the Mamertines to accept a Carthaginian garrison in Messana. Either unhappy with the prospect of a Carthaginian garrison or convinced that the recent alliance between Rome and Carthage against Pyrrhus reflected cordial relations between the two, the Mamertines, hoping for more reliable protection, petitioned Rome for an alliance.
However, the rivalry between Rome and Carthage had grown since the war with Pyrrhus and that alliance was no longer feasible. According to the historian Polybius, considerable debate took place in Rome on the questio
The Histories (Polybius)
Polybius’ Histories were written in 40 volumes, only the first five of which are extant in their entirety. The bulk of the work was passed down through collections of excerpts kept in libraries in Byzantium. Polybius, a historian from the Greek city of Megalopolis in Arcadia, was taken as a hostage to Rome after the Roman defeat of the Achaean League, there he began to write an account of the rise of Rome to a world power. Polybius' Histories begin in the year 264 BC and end in 146 BC, he is concerned with the 53 years in which Ancient Rome became a dominant world power. This period, from 220 -- 167 BC, saw gain control over Hellenistic Greece. Books I through V cover the affairs of important states at the time and deal extensively with the First and Second Punic Wars. In Book VI he describes the Roman Constitution and outlines the powers of the consuls and People, he concludes that the success of the Roman state was based on their mixed constitution, which combined elements of a democracy and monarchy.
The remainder of the Histories discusses the period in which Rome came to dominate the Mediterranean, from the defeat of Hannibal in 201 B. C. to the destruction of Carthage and the Greek city-state of Corinth in 146 B. C. Tyche, which means fate or fortune, plays an integral role in Polybius’ understanding of history. Tyche takes on a double meaning in his work, it can mean fortune or happenstance, but tyche was personified as a goddess according to Hellenistic convention. The exploration of Tyche is the impetus for Polybius beginning his work, in that he discusses the fortunate events that led to Rome’s domination of the Mediterranean. In Book VI Polybius digresses into an explanation of the Roman constitution and he shows it to be mixed; the purpose for this is involved in the Hellenistic nature of the work his Greek audience. Greeks at this time believed that the strength of a state is manifested in the strength of its constitution; the mixed constitution was touted as the strongest constitution as it combined the three integral types of government: monarchy and democracy.
Polybius makes further distinction in the forms of government by including the nefarious counterparts to the ones mentioned above. These governments, according to Polybius, cycle in a process called anacyclosis, which begins with monarchy and ends with ochlocracy; the Romans avoided this problem through the structure of their Republic. The first English translation, made by Christopher Watson, was published in London in 1568 as The hystories of the most famous and worthy cronographer Polybius. F. W. Walbank wrote a comprehensive commentary on the Histories in three volumes, published in 1957. Herodotus Thucydides Xenophon Mogens Herman Hansen 1995, Sources for the Ancient Greek City-State: Symposium, August, 24-27 1994, Kgl. Danske, Videnskabernes Selskab, 376 pages ISBN 87-7304-267-6 Robert Pashley, Travels in Crete, 1837, J. Murray C. Michael Hogan, Jan. 23, 2008, The Modern Antiquarian Polybius. The Rise of the Roman Empire. Penguin Classics. ISBN 0-14-044362-2. English and Greek version The Histories Translation by W. R. Paton Short introduction to the life and work of Polybius Polybius and the Founding Fathers: the separation of powers
A heliograph is a wireless telegraph that signals by flashes of sunlight reflected by a mirror. The flashes are produced by momentarily pivoting the mirror, or by interrupting the beam with a shutter; the heliograph was a simple but effective instrument for instantaneous optical communication over long distances during the late 19th and early 20th century. Its main uses were military and forest protection work. Heliographs were standard issue in the British and Australian armies until the 1960s, were used by the Pakistani army as late as 1975. There were many heliograph types. Most heliographs were variants of the British Army Mance Mark V version, it used a mirror with a small unsilvered spot in the centre. The sender aligned the heliograph to the target by looking at the reflected target in the mirror and moving their head until the target was hidden by the unsilvered spot. Keeping their head still, they adjusted the aiming rod so its cross wires bisected the target, they turned up the sighting vane, which covered the cross wires with a diagram of a cross, aligned the mirror with the tangent and elevation screws so the small shadow, the reflection of the unsilvered spot hole was on the cross target.
This indicated. The flashes were produced by a keying mechanism that tilted the mirror up a few degrees at the push of a lever at the back of the instrument. If the sun was in front of the sender, its rays were reflected directly from this mirror to the receiving station. If the sun was behind the sender, the sighting rod was replaced by a second mirror, to capture the sunlight from the main mirror and reflect it to the receiving station; the U. S. Signal Corps heliograph mirror did not tilt; this type produced flashes by a shutter mounted on a second tripod. The heliograph had some great advantages, it allowed long distance communication without a fixed infrastructure, though it could be linked to make a fixed network extending for hundreds of miles, as in the fort-to-fort network used for the Geronimo campaign. It was portable, did not require any power source, was secure since it was invisible to those not near the axis of operation, the beam was narrow, spreading only 50 feet per mile of range.
However, anyone in the beam with the correct knowledge could intercept signals without being detected. In the Boer War, where both sides used heliographs, tubes were sometimes used to decrease the dispersion of the beam. In some other circumstances, though, a narrow beam made it difficult to stay aligned with a moving target, as when communicating from shore to a moving ship, so the British issued a dispersing lens to broaden the heliograph beam from its natural diameter of 0.5 degrees to 15 degrees. The distance that heliograph signals could be seen depended on the clarity of the sky and the size of the mirrors used. A clear line of sight was required, since the Earth's surface is curved, the highest convenient points were used. Under ordinary conditions, a flash could be seen 30 miles with the naked eye, much farther with a telescope; the maximum range was considered to be 10 miles for each inch of mirror diameter. Mirrors ranged from 1.5 inches to 12 inches or more. The record distance was established by a detachment of U.
S. signal sergeants by the inter-operation of stations on Mount Ellen and Mount Uncompahgre, Colorado, 183 miles apart on September 17, 1894, with Signal Corps heliographs carrying mirrors only 8 inches square. The German professor Carl Friedrich Gauss of the University of Göttingen developed and used a predecessor of the heliograph in 1821, his device directed a controlled beam of sunlight to a distant station to be used as a marker for geodetic survey work, was suggested as a means of telegraphic communications. This is the first reliably documented heliographic device, despite much speculation about possible ancient incidents of sun-flash signalling, the documented existence of other forms of ancient optical telegraphy. For example, one author in 1919 chose to "hazard the theory" that the mainland signals Roman emperor Tiberius watched for from Capri were mirror flashes, but admitted "there are no references in ancient writings to the use of signaling by mirrors", that the documented means of ancient long-range visual telecommunications was by beacon fires and beacon smoke, not mirrors.
The story that a shield was used as a heliograph at the Battle of Marathon is a modern myth, originating in the 1800s. Herodotus never mentioned any flash. What Herodotus did write was that someone was accused of having arranged to "hold up a shield as a signal". Suspicion grew in the 1900s; the conclusion after testing the theory was "Nobody flashed a shield at the Battle of Marathon". In a letter dated 3 June 1778, John Norris, High Sheriff of Buckinghamshire, notes: "Did this day heliograph intelligence from Dr Franklin in Paris to Wycombe". However, there is little evidence that "heliograph" here is other than a misspelling of "holograph"; the term "heliograph" for solar telegraphy did not enter the English language until the 1870s—even the word "telegraphy" was not coined until the 1790s. Henry Christopher Mance, of the British Government Persian Gulf Telegraph Department, developed the first accepted heliograph about 1869 while stationed at Karachi, in the Bombay Presidency in British India.
Mance was familiar with heliotropes by their use for the Great India Survey. The Mance Heliograph was operated by one man, since it weighed about seven pounds, the operator could carry the devi
Hydraulics is a technology and applied science using engineering and other sciences involving the mechanical properties and use of liquids. At a basic level, hydraulics is the liquid counterpart of pneumatics, which concerns gases. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the applied engineering using the properties of fluids. In its fluid power applications, hydraulics is used for the generation and transmission of power by the use of pressurized liquids. Hydraulic topics range through some parts of science and most of engineering modules, cover concepts such as pipe flow, dam design and fluid control circuitry; the principles of hydraulics are in use in the human body within the vascular system and erectile tissue. Free surface hydraulics is the branch of hydraulics dealing with free surface flow, such as occurring in rivers, lakes and seas, its sub-field open-channel flow studies the flow in open channels. The word "hydraulics" originates from the Greek word ὑδραυλικός which in turn originates from ὕδωρ and αὐλός.
Early uses of water power date back to Mesopotamia and ancient Egypt, where irrigation has been used since the 6th millennium BC and water clocks had been used since the early 2nd millennium BC. Other early examples of water power include the Qanat system in ancient Persia and the Turpan water system in ancient Central Asia; the Greeks constructed sophisticated water and hydraulic power systems. An example is the construction by Eupalinos, under a public contract, of a watering channel for Samos, the Tunnel of Eupalinos. An early example of the usage of hydraulic wheel the earliest in Europe, is the Perachora wheel; the construction of the first hydraulic automata by Ctesibius and Hero of Alexandria is notable. Hero describes a number of working machines using hydraulic power, such as the force pump, known from many Roman sites as having been used for raising water and in fire engines; the Persians constructed an intricate system of water mills and dams known as the Shushtar Historical Hydraulic System.
The project, commenced by Achaemenid king Darius the Great and finished by a group of Roman engineers captured by Sassanian king Shapur I, has been referred to by UNESCO as "a masterpiece of creative genius." They were the inventors of the Qanat, an underground aqueduct. Several of Iran's large, ancient gardens were irrigated thanks to Qanats. In ancient China there was Sunshu Ao, Ximen Bao, Du Shi, Zhang Heng, Ma Jun, while medieval China had Su Song and Shen Kuo. Du Shi employed a waterwheel to power the bellows of a blast furnace producing cast iron. Zhang Heng was the first to employ hydraulics to provide motive power in rotating an armillary sphere for astronomical observation. In ancient Sri Lanka, hydraulics were used in the ancient kingdoms of Anuradhapura and Polonnaruwa; the discovery of the principle of the valve tower, or valve pit, for regulating the escape of water is credited to ingenuity more than 2,000 years ago. By the first century AD, several large-scale irrigation works had been completed.
Macro- and micro-hydraulics to provide for domestic horticultural and agricultural needs, surface drainage and erosion control and recreational water courses and retaining structures and cooling systems were in place in Sigiriya, Sri Lanka. The coral on the massive rock at the site includes cisterns for collecting water. Large ancient reservoirs of Sri Lanka are Kalawewa, Parakrama Samudra, Tisa Wewa, Minneriya In Ancient Rome, many different hydraulic applications were developed, including public water supplies, innumerable aqueducts, power using watermills and hydraulic mining, they were among the first to make use of the siphon to carry water across valleys, used hushing on a large scale to prospect for and extract metal ores. They used lead in plumbing systems for domestic and public supply, such as feeding thermae. Hydraulic mining was used in the gold-fields of northern Spain, conquered by Augustus in 25 BC; the alluvial gold-mine of Las Medulas was one of the largest of their mines. It was worked by at least 7 long aqueducts, the water streams were used to erode the soft deposits, wash the tailings for the valuable gold content.
In 1619 Benedetto Castelli, a student of Galileo Galilei, published the book Della Misura dell'Acque Correnti or "On the Measurement of Running Waters", one of the foundations of modern hydrodynamics. He served as a chief consultant to the Pope on hydraulic projects, i.e. management of rivers in the Papal States, beginning in 1626. Blaise Pascal studied fluid hydrodynamics and hydrostatics, centered on the principles of hydraulic fluids, his discovery on the theory behind hydraulics led to the invention of the hydraulic press by Joseph Bramah, which multiplied a smaller force acting on a smaller area into the application of a larger force totaled over a larger area, transmitted through the same pressure at both locations. Pascal's law or principle states that for an incompressible fluid at rest, the difference in pressure is proportional to the difference in height and this difference remains the same whether or not the overall pressure of the fluid is changed by applying an external force.
This implies that by increasing the pressure at any point in a confined fluid, there is an equal increase at every other point in the containe
Optical communication known as optical telecommunication, is communication at a distance using light to carry information. It can be performed visually or by using electronic devices; the earliest basic forms of optical communication date back several millennia, while the earliest electrical device created to do so was the photophone, invented in 1880. An optical communication system uses a transmitter, which encodes a message into an optical signal, a channel, which carries the signal to its destination, a receiver, which reproduces the message from the received optical signal; when electronic equipment is not employed the'receiver' is a person visually observing and interpreting a signal, which may be either simple or complex. Free-space optical communication has been deployed in space, while terrestrial forms are limited by geography and the availability of light; this article provides a basic introduction to different forms of optical communication. Visual techniques such as smoke signals, beacon fires, hydraulic telegraphs, ship flags and semaphore lines were the earliest forms of optical communication.
Hydraulic telegraph semaphores date back to the 4th century BCE Greece. Distress flares are still used by mariners in emergencies, while lighthouses and navigation lights are used to communicate navigation hazards; the heliograph uses a mirror to reflect sunlight to a distant observer. When a signaler tilts the mirror to reflect sunlight, the distant observer sees flashes of light that can be used to transmit a prearranged signaling code. Naval ships use signal lamps and Morse code in a similar way. Aircraft pilots use visual approach slope indicator projected light systems to land safely at night. Military aircraft landing on an aircraft carrier use a similar system to land on a carrier deck; the coloured light system communicates the aircraft's height relative to a standard landing glideslope. As well, airport control towers still use Aldis lamps to transmit instructions to aircraft whose radios have failed. In the present day a variety of electronic systems optically transmit and receive information carried by pulses of light.
Fiber-optic communication cables are now employed to send the great majority of the electronic data and long distance telephone calls that are not conveyed by either radio, terrestrial microwave or satellite. Free-space optical communications are used every day in various applications. A'semaphore telegraph' called a'semaphore line','optical telegraph','shutter telegraph chain','Chappe telegraph', or'Napoleonic semaphore', is a system used for conveying information by means of visual signals, using towers with pivoting arms or shutters known as blades or paddles. Information is encoded by the position of the mechanical elements. Semaphore lines were a precursor of the electrical telegraph, they were far faster than post riders for conveying a message over long distances, but far more expensive and less private than the electrical telegraph lines which would replace them. The maximum distance that a pair of semaphore telegraph stations can bridge is limited by geography and the availability of light.
Each relay station would require its complement of skilled operator-observers to convey messages back and forth across the line. The modern design of semaphores was first foreseen by the British polymath Robert Hooke, who first gave a vivid and comprehensive outline of visual telegraphy in a 1684 submission to the Royal Society, his proposal was not put into practice during his lifetime. The first operational optical semaphore line arrived in 1792, created by the French engineer Claude Chappe and his brothers, who succeeded in covering France with a network of 556 stations stretching a total distance of 4,800 kilometres, it was used for military and national communications until the 1850s. Many national services adopted signaling systems different from the Chappe system. For example and Sweden adopted systems of shuttered panels. In Spain, the engineer Agustín de Betancourt developed his own system, adopted by that state; this system was considered by many experts in Europe better than Chappe's in France.
These systems were popular in the late 18th to early 19th century but could not compete with the electrical telegraph, went out of service by 1880. Semaphore Flags is the system for conveying information at a distance by means of visual signals with hand-held flags, disks, paddles, or bare or gloved hands. Information is encoded by the position of the flags, objects or arms. Semaphores were adopted and used in the maritime world in the 19th century, they are still used during underway replenishment at sea and are acceptable for emergency communication in daylight or, using lighted wands instead of flags, at night. The newer flag semaphore system uses two short poles with square flags, which a signaler holds in different positions to convey letters of the alphabet and numbers; the transmitter holds one pole in each hand, extends each arm in one of eight possible directions. Except for in the rest position, the flags cannot overlap; the flags are colored differently based on whether the signals are sent by sea or b
A signal lamp is a visual signaling device for optical communication using Morse code. Modern signal lamps are focused lamps. In large versions, this pulse is achieved by opening and closing shutters mounted in front of the lamp, either via a manually operated pressure switch, or, in versions, automatically. With hand held lamps, a concave mirror is tilted by a trigger to focus the light into pulses; the lamps were equipped with some form of optical sight, were most used on naval vessels and in airport control towers. In manual signaling, a signalman would aim the light at the recipient ship and turn a lever and closing the shutter over the lamp, to emit flashes of light to spell out text messages in Morse code. On the recipient ship, a signalman would observe the blinking light with binoculars, translate the code into text. Signal lamps were pioneered by the Royal Navy in the late 19th century and continue to be used to the present day on naval vessels, they provide handy secure communications, which are useful during periods of radio silence, such as for convoys operating during the Battle of the Atlantic.
There are several types. Some signal lamps are mounted on the mastheads of ships, some small hand-held versions are used; these larger ones use a carbon arc lamp with a diameter of 20 inches. These can be used to signal to the horizon in conditions of bright sunlight. Although it was thought that it was only possible to communicate by line-of-sight, in practice it is possible to illuminate cloud bases both during the night and day, which allow for communication beyond the horizon; the maximum transmission rate possible via flashing lights is no more than 14 wpm. They have a secondary function as simple spotlights; the idea of flashing dots and dashes from a lantern was first put into practice by Captain Vice Admiral, Philip Colomb, of the British Royal Navy, in 1867. His original code, which the Navy used for seven years, was not identical with Morse's, but Morse code was adopted with the addition of several special signals. Another signalling lamp was the Begbie lamp, a kerosene lamp with a lens to focus the light over a long distance.
Flashing lights were the second generation of signalling in the Royal Navy, after the flag signals most famously used to spread Nelson's rallying-cry before the Battle of Trafalgar. During the trench warfare of World War I when wire communications were cut, German signals used three types of optical Morse transmitters, called Blinkgerät, the intermediate type for distances of up to 4 km at daylight and of up to 8 km at night, using red filters for undetected communications; the Commonwealth navies and NATO forces use signal lamps when radio communications need to be silent or electronic "spoofing" is likely. Given the prevalence of night vision equipment in today's armed forces, signaling at night is done with lights that operate in the infrared spectrum, making them less to be detected. All modern forces have followed suit due to technological advances in digital communications. In air traffic control towers, signal lamps are still used today, as a backup device in case of a complete failure of an aircraft's radio.
Light signals can be green, red, or white, steady or flashing. Messages are limited to a handful of basic instructions. Aircraft can acknowledge signals by flashing their landing lights. Colt Acetylene Flash Lantern Flag semaphore Heliograph An Aldis lamp in operation