The Royal Observatory, Greenwich is an observatory situated on a hill in Greenwich Park in south east London, overlooking the River Thames to the north. It played a major role in the history of astronomy and navigation, and because the Prime Meridian passes through it, it gave its name to Greenwich Mean Time, the precursor to today's Coordinated Universal Time (UTC). The ROG has the IAU observatory code of 000, the first in the list. ROG, the National Maritime Museum, the Queen's House and the clipper ship Cutty Sark are collectively designated Royal Museums Greenwich.
An optical telegraph is a line of stations, typically towers, for the purpose of conveying textual information by means of visual signals. There are two main types of such systems; the semaphore telegraph which uses pivoted indicator arms and conveys information according to the direction the indicators point, and the shutter telegraph which uses panels that can be rotated to block or pass the light from the sky behind to convey information.
The Downs is a roadstead in the southern North Sea near the English Channel off the east Kent coast, between the North and the South Foreland in southern England. In 1639 the Battle of the Downs took place here, when the Dutch navy destroyed a Spanish fleet which had sought refuge in neutral English waters. From the Elizabethan era onwards, the presence of the Downs helped to make Deal one of the premier ports in England, and in the 19th century, it was equipped with its own telegraph and timeball tower to enable ships to set their marine chronometers.
Sir George Biddell Airy was an English mathematician and astronomer, and the seventh Astronomer Royal from 1835 to 1881. His many achievements include work on planetary orbits, measuring the mean density of the Earth, a method of solution of two-dimensional problems in solid mechanics and, in his role as Astronomer Royal, establishing Greenwich as the location of the prime meridian.
Sir Francis Beaufort was an Irish hydrographer, creator of the Beaufort cipher and the Beaufort scale, and naval officer.
Dover is a local government district in Kent, England. It is named after its largest town, the port town of Dover. The council is based in Whitfield on the outskirts of Dover. The district also covers the towns of Deal, Sandwich, Walmer and the surrounding rural areas.
A time ball or timeball is a time-signalling device. It consists of a large, painted wooden or metal ball that is dropped at a predetermined time, principally to enable navigators aboard ships offshore to verify the setting of their marine chronometers. Accurate timekeeping is essential to the determination of longitude at sea.
Sir Charles Todd worked at the Royal Greenwich Observatory 1841–1847 and the Cambridge University observatory from 1847 to 1854. He then worked on telegraphy and undersea cables until engaged by the government of South Australia as astronomical and meteorological observer, and head of the electric telegraph department.
The Sea Fencibles were naval fencible units established to provide a close-in line of defence and obstruct the operation of enemy shipping, principally during the French Revolutionary and Napoleonic Wars.
Blackhead Point, also known as Tai Pau Mai indigenously, or by the names Tsim Sha Tsui Point and Signal Hill (訊號山), was a cape before any land reclamation took place in Tsim Sha Tsui, Kowloon, Hong Kong. It currently remains a small hill near the coast.
Charles Frodsham was a distinguished English horologist, establishing the firm of Charles Frodsham & Co, which remains in existence as the longest continuously trading firm of chronometer manufacturers in the world. In January 2018, the firm launched a new chronometer wristwatch, after sixteen years in development. It is the first watch to use the George Daniels double-impulse escapement.
The Shepherd Gate Clock is mounted on the wall outside the gate of the Royal Observatory, Greenwich building in Greenwich, Greater London. The clock, an early example of an electrically connected clock system, was a sympathetic clock mechanism controlled by electric pulses transmitted by a motor clock inside the main building. The network of 'sympathetic clocks' was constructed and installed by Charles Shepherd in 1852. The clock by the gate was probably the first to display Greenwich Mean Time to the public, and is unusual in using the 24-hour analog dial. Also it originally showed astronomical time which started at 12 noon not midnight.
Charles Vincent Walker FRS was an English electrical engineer and publisher, a major influence on the development of railway telecommunications, he was also the first person to send a submarine telegraph signal.
John Thomas Serres was an English maritime painter who enjoyed significant success, including exhibiting extensively at the Royal Academy, and was for a time Maritime Painter to King George III.
Vice-Admiral Sir John Gilchrist Thesiger Inglis,, sometimes known as Tommy Inglis, was a Royal Navy officer who served as Director of Naval Intelligence from 1954 to 1960. In this capacity, he attempted to cover-up the "Buster Crabb affair" in 1956.
The IERS Reference Meridian (IRM), also called the International Reference Meridian, is the prime meridian maintained by the International Earth Rotation and Reference Systems Service (IERS). It passes about 5.3 arcseconds east of George Biddell Airy's 1851 transit circle which is 102 metres (335 ft) at the latitude of the Royal Observatory, Greenwich. Thus it differs slightly from the historical Greenwich meridian.
The 1874 Transit of Venus Expedition to Hawaii was an astronomical expedition by British scientists to observe the December 8 transit of Venus at three separate observing sites in the Hawaiian Islands, then known as the Sandwich Islands. It was one of five 1874 transit expeditions organized by George Biddell Airy, Astronomer Royal at the Royal Observatory, Greenwich. The purpose of the expedition was to obtain an accurate estimate of the astronomical unit (AU), the distance from the Earth to the Sun, by measuring solar parallax. Previous efforts to obtain a precise value of an AU in 1769 had been hampered by the black drop effect. There is a collection of papers relating to this expedition at the Cambridge Digital Library.
The Glorious Revolution of 1688 rearranged the political map of Europe, and led to a series of wars with France that lasted well over a century. This was the classic age of sail; while the ships themselves evolved in only minor ways, technique and tactics were honed to a high degree, and the battles of the Napoleonic Wars entailed feats that would have been impossible for the fleets of the 17th century. Because of parliamentary opposition, James II fled the country. The landing of William III and the Glorious Revolution itself was a gigantic effort involving 100 warships and 400 transports carrying 11,000 infantry and 4,000 horses. It was not opposed by the English or Scottish fleets.
The Department of the Permanent Secretary also formally known as the Department of the Permanent Secretary to the Admiralty or the Department of the Secretary was the Civil Service department responsible for the control, direction and guidance of all administrative functions of the British Admiralty from 1702 to 1964, it was headed by the Permanent Secretary to the Admiralty.
