This technical textbook is the nineteenth edition of the book by Henry Raper, Lieutenant in the Royal Navy with awards that include F.R.A.S. (Fellow of the Royal Astronomical Society) and F.R.G.S. (Friend of the Royal Geographical Society). The book is dedicated in honour of Rear-Admiral Sir Francis Beaufort K.C.B., Hydrographer to the Admiralty. He was awarded the title K.C.B. (King's Commander) as a Member of the Order of Bath, an order of British Chivalry, The book was first published in 1840 and soon became a resource for navigation students. It includes topics on nautical navigation, astronomy, navigation charts, calculations and mathematical tables, time, tides, ships, longitude, and position at sea. Thomas A. Hull, who revised and expanded this edition, was a Commander in the Royal Navy and had previously been Superintendent of Admiralty Charts used for navigation worldwide by seamen from many walks of life. The publisher, J D Potter of London, was at that time the sole agent for the Admiralty Charts produced by the Royal Navy. Printer Spottswoode and Co.,. was established by William Strachan in 1738. In 1819 his nephews A and R Spottswoode took over the business and bought premises in New-Street Square and Shoe Lane. In 1850 over 200 workers were employed by the firm. and five years later the business became Spottswoode & Co. Andrew Spottswoode invented the Spottswoode Press.This technical book was very popular as a textbook for students of maritime navigation, written and updated by members of the British Royal Navy and relied upon for accurate advice and information. The first edition was published in 1840, this edition was updated, expanded and published in 1891 when ports around the world were filling with travellers, merchants and business people. Title: The Practice of Navigation and Nautical Astronomy Author: Henry Raper, Lieut, R.N., F.R.A.S., F.R.G.S. Nineteenth Edition, revised and enlarged by Commander Thomas A. Hull, R.N., Late Superintendant of Admiralty Charts Dedication: To Rear-Admiral Sir Francis Beaufort K.C.B. Publisher: J D Potter, London, sole agent for the sale of Admiralty Charts Printer: Spottswoode and Co. New-Street Square, London Date: 1891 Small leather hardcover book with gold embossed text and lines on the spine. The Dedication in the book is as follows: - "To Rear-Admiral Sir Francis Beaufort K.C.B. Hydrographer to the Admiralty. Sir, The eminent station which you occupy in the naval scientific world renders it highly gratifying to me to dedicate the following Work to you as a testimony of my regard and esteem; while the general accordance of my views on the subject with those of your more experienced judgement, gives me the greater confidence in laying my labours before the Public. I have the honour to be, Sir, Your obedient servant, HENRY RAPER"flagstaff hill maritime museum, maritime museum, shipwreck coast, flagstaff hill, warrnambool, flagstaff hill maritime village, book, navigation, nautical astronomy, hydrography, nautical charts, nautical navigation, astronomical navigation, admiralty charts, henry raper, thomas a. hull, royal navy, j d potter, royal astronomical society, royal geographical society, calculations, mathematical tables, longitude, latitude, nautical time, location at sea, position at sea, maritime, practical navigation, spottswoode and co., sir francis beaufort, k.c.b., rear-admiral sir francis beaufort, hydrographer to the admiralty, scientific book, naval science

This mounted chart, dated 21 August 1971 is under glass in a wooden frame and covers Bass Strait between Cape Otway and Gabo Island, showing southern and eastern Victoria and the whole of Tasmania. The frame was possibly handmade locally. The charts are specific to the Gabo Island Lightstation and have second level contributory significance for their historic value and provenance to the lightstation.Blue / grey & white nautical chart of Cape Otway to Gabo Island . It is under glass and in a white painted wooden frame. The frame has three holes at the top left and the base.Top left-hand," AUS 422 DEPTHS IN FATHOMS......."

Used as display in AMSA workshop foyer, Moorabbin, Vic. Nautical charts x 2 , The framed and glazed chart identifies strategic points in the notorious Bass Strait passage, which in the nineteenth century was known as the ‘Eye of the Needle’. It covers the whole of Tasmania, Bass Strait and the islands, and the lower part of Victoria with its coastline between Cape Otway and Gabo Island. The chart has an electric cord connecting it to a wall switch which enables a series of small lights to flash on strategic geographical locations.. While it is not known if it is original to Wilsons Promontory, it certainly elates to its location. A similar chart at Cape Otway shows less of Tasmania and is not electrified. Gabo Island Lightstation has two large framed charts; one is the same as the Wilsons Promontory example but without the lights and the other is entirely different, focussing on the east coast between Point Hicks and Montague Island. The Wilsons Promontory chart is unique as an illuminated version of the other charts and has first level significance if its provenance to the lightstation can be confirmed.The framed and glazed chart has an electric cord connecting it to a wall switch which enables a series of small lights to flash on strategic geographical locations.Yes

This journal provides the reader with glimpses of the adventures and hardships of a seaman's life. Many of the stories are of sailing ships.Contributes to our knowledge of the importance of shipping and places on record those stories of the sea which would otherwise be lost.Contents Foreword - 5 Editorial - 7 'Sunbeam' and 'Sunbeam 2' - 11 Queer Convoy of the Pacific - 19 Port Phillip Mutinies of the 1850s - 24 Boiler-Room Bedlam - 26 The Nautical Chart - 30 The Challenge of the Sea - 32 Flagstaff Hill Maritime Village - 33 A Wonderful Gift - 34 The Dhow Sailors - 35 My Second Ship - 45 We Star our Voyage - 53 Peril in Ice - 58 L ' Avenir Apprentice - 61 Of Sharks and Such - 71 Submarine Duty 1918 - 75 The 'Samuel Plimosll' - 84 The 'Marco Polo's' Voyage - 85 Tarry Barry -- Keep-Water Man - 95 The Albatross - 99 At Quiet Moorings I Recall - 100 "Oh, But I'm Longing for me Ain Folk" - 104 Remedy for Stowaways - 105 The Little Ship - 106 Comments on 'My First Ship' - 109 Not a Soft Answer - 110 Just a Little Too Much of a Good Thing - 111 Early History of the 'Regina Maris' - 113 The Development of Lakes Entrance - 115 Book Reviews - 119sailing ships, steamships, shipping, seafaring life, shiplovers' society of victoria, dog watch

An Octant is a doubly reflecting navigation instrument used primarily by sailors to measure the angular distance between two visible objects and was a forerunner of the sextant. The name comes from the Latin octo, or “one-eighth of a circle,” for the Octant’s arc which spans 45°, or one-eighth of a circle. The primary use of an Octant is to measure the angle between an astronomical object and the horizon for the purposes of celestial navigation. The estimation of this angle is known as sighting or shooting the object, or taking a sight. The angle, and the time when it was measured, can be used to calculate a position line on a nautical chart (latitude), for example, sighting the Sun at noon or Polaris at night (in the Northern Hemisphere) gives an angle by which the latitude can then be estimated. Sighting the height of a landmark on land can also give a measure of distance. History: The principle of the Octant as an instrument to measure ones latitude was first implemented around 1742-present but was superseded by the improvement of the octant to a sextant, a very similar instrument, better made and able to measure bigger angles 120°, allowing the measurement of Luna distances to give longitude when used with an accurate chronometer. The sextant started to appear around 1730 and had been attributed to by John Hadley (1682–1744) and Thomas Godfrey (1704–1749), but reference to the sextant was also found later in the unpublished writings of Isaac Newton (1643–1727). Earlier links can be found to Bartholomew Gosnold (1571–1607) indicating that the use of a Sextant for nautical navigation predates Hadley's implementation. In 1922, the sextant was modified for aeronautical navigation by Portuguese navigator and naval officer Gago Coutinho. Henry Hemsley was a lesser-known instrument maker and optician working in London in the late 17th and early 18th century. However, it should be noted that there were two Henry Hemsley opticians and instrument makers around this period. (Henry Hemsley 1, 1786-89, who had premises at 85 Fleet St London and Henry Hemsley 2, 1828-56), whose workshop was at 135-138 Radcliff Highway London. Therefore, based on the inscribed workshop address Henry Hemsley 2 is responsible for making this example.The octant is representative of its type and although not fully complete it demonstrates how 18th and 19th-century mariners determined their latitude on a chart to navigate their way across the world's oceans in the 18th and 19th century. It also demonstrates the skill and workmanship of the early instrument makers that operated from London at this time and provided most of the navigational instrumentation use by commercial and military navies of the time.Octant, ebony wooden frame and handle. Scale is missing from recess in frame. "H. Hemsley 135-138 Ratliff Highway, London", no box"H. Hemsley 135-138 Ratcliff Highway, London"flagstaff hill, warrnambool, shipwrecked-coast, flagstaff-hill, flagstaff-hill-maritime-museum, maritime-museum, shipwreck-coast, flagstaff-hill-maritime-village, navigation, navigational instrument, instrument used for navigation, sextant, henry hemsley, instrument maker, london, octant

An Octant is a doubly reflecting navigation instrument used primarily by sailors to measure the angular distance between two visible objects and was a forerunner of the sextant. The name comes from the Latin octo, or "one-eighth of a circle," for the Octan'ts arc which spans 45°, or one-eighth of a circle. The primary use of an Octant is to measure the angle between an astronomical object and the horizon for celestial navigation. The estimation of this angle, is known as sighting or shooting the object, or taking a sight. The angle, and the time when it was measured, can be used to calculate a position line on a nautical chart (latitude), for example, sighting the Sun at noon or Polaris at night (in the Northern Hemisphere) gives an angle by which the latitude can then be estimated. Sighting the height of a landmark on land can also give a measure of distance. This fine octant once belonged to Captain Farquhar Chisholm and was donated by his granddaughter, Margaret Ruth Greer (nee Chisholm, born 1914). The label inside the Octant's box reads “Thomas L. Ainsley, Instrument Maker … etc”. Farquhar Chisholm was born in 1832 in Inverness, Scotland. He regularly sailed on perilous voyages between Quebec, Canada and the Baltic ports of Europe. In 1854 he migrated to Australia during the Gold Rush, to a place called Fiery Creek (near Beaufort Victoria) where he was fairly successful in his quest for gold. In the years of the Great Gold Rush, it was said that there were over 40,000 diggers in the goldfields of the Beaufort area! In 1857 having made sufficient money, he hired another crew and returned to Clachnacuddin, Inverness shire, Scotland and in that same year, he studied and obtained his Master Mariner Certificate (which would have included the use of an octant for navigation). He was appointed to Mr George (or James) Walker, as commander of his sailing ship, the 3-masted ELIZABETH, built 1859 and known as “The Walker barque”. In 1870 he married, then in 1887 returned to Australia with his wife and children (Kenneth Chisholm (1871), Mary Bremner Chisholm (1873), Margaret Hood Chisholm (1874), Farquhar Chisholm (1878)). They arrived in Port Melbourne, Victoria and sadly, only six weeks after landing, his wife Caroline passed away (in Geelong,1888). In 1900 Capt. Chisholm lived in Camperdown (Victoria) and not long after this his daughter Margaret died of consumption. In his later years, he went to live in the manse of St. Paul’s Presbyterian Church, Wangaratta, with his son, Rev. Farquhar Chisholm. He died there on Sat, 23rd March 1912, 80 years old. He was known as “… quiet, unobtrusive and competent, respected by all with whom he came in contact”. Some other members of Captain Chisholm’s family are; his older son Kenneth Chisholm, who was a contractor in Camperdown; a nephew Donald Macintosh (of 23 Douglas Row, Inverness); a grandson Brian Jones (son of Caroline Belle-Jones nee Chisholm, who lived in Camperdown in the earlier part of her life).The octant, the forerunner of the sextant, was a significant step in providing accuracy of a sailors latitude position at sea & his vessels distance from land when taking sightings of land-based landmarks.Octant, once belonging to Captain Farquhar Chisholm. Wedge shape (the size of an eighth of a circle), made of wood, glass and metal. Used in the 1880s. Maker’s name across centre “L. SIMON - - - SHIELDS”. Three (3) light filtering, coloured glass shades. Two (2) eyepieces. Scale attached for measuring angles. Label inside the fitted, wedge-shaped case "Thomas L. Ainsley, Optician"Label inside case "Thomas L. Ainsley, Optician" Maker’s name across centre “L. SIMON - - - SHIELDS”.flagstaff hill, warrnambool, shipwrecked-coast, flagstaff-hill, flagstaff-hill-maritime-museum, maritime-museum, shipwreck-coast, flagstaff-hill-maritime-village, maritime navigation, navigation instrument, migration, captain chisholm, farquhar chisholm, sailing ship, the elizabeths, thomas l. ainsley, l. simons, shields england, octant, john hadley, chisholm

All of these Charts / Maps were used for the RSL Museum display " The Mapmakers " ( of RASvy. ) 10 Jun - 10 Aug 2025. .1 Catalogue of Tactical Pilotage Charts, 1:500 000 Scale. Digital Data Base available as at 30Jun 92. This catalogue page shows the extent of the Australian area of responsibility for aeronautical charting. .2 RAAF PLOTTING CHART. NP 22-2 (Navigational Plotting) Tasmania. MERCATOR PROJECTION. This series of charts were used for the training of RAAF Navigators. These charts were produced and printed at the Army Survey Regiment, Bendigo. .3 RAAF PLOTTING CHART AUSTRALIA - SOUTHEAST. NP 27 is Based on LAMBERT CONFORMAL CONIC PROJECTION. This series of charts was used by RAAF Navigators for the planning of RAAF flights. These charts were produced and printed at the Army Survey Regiment, Bendigo. .4 RAAF LONG RANGE PLOTTING CHART. NP 43-4 AUSTRALIA WESTERN. MERCATOR PROJECTION. This series of maps were used for the planning of RAAF flights. Of Particular note these charts were used to plot "Rhumb Lines or loxodromes" where a course crosses all Meridians (Lines of latitude and longitude) at the same angle. On Mercator projection charts Rhumb lines are conveniently shown as straight lines and are also lines of constant compass bearing. Rhumb lines are usually longer than the shortest distance between two points. The shortest distance between two points on the earth's surface is called a "Great Circle Route" which is a route on a circular path on the surface of the earth where the centre of that circle is also the centre of the earth. Great Circle Routes on a Mercator Projection are however curves and harder to plot. These charts were produced and printed at the Army Survey Regiment, Bendigo. .5 RAAF LONG RANGE PLOTTING CHART. NP 43-7 SOLOMON ISLANDS. MERCATOR PROJECTION. Used for the planning of RAAF flights. .6 RAAF AIR STAFF PLANNING CHART NS 137-1 DARWIN NORTH WEST. AZIMUTHAL EQUIDISTANT PROJECTION. This series of charts were used for planning by the staff. The whole chart was produced by joining the four quadrant maps together. The charts are based on a single point of tangency (in this case Darwin) and shows radius (distance) in nautical miles to and from that point. A series of charts were produced centred on each of the major airfields in Northern Australia. These charts were produced and printed at the Army Survey Regiment, Bendigo. .7 RAAF AIR STAFF PLANNING CHART NS 137-2 DARWIN NORTH EAST. AZIMUTHAL EQUIDISTANT PROJECTION. Used for the planning by the staff. The charts are based on a point of tangency and show radius in nautical miles. .8 RAAF AIR STAFF PLANNING CHART NS 137-4 DARWIN SOUTH WEST. AZIMUTHAL EQUIDISTANT PROJECTION. Used for the planning by the staff. The charts are based on a point of tangency and show radius in nautical miles. .9 RAAF AIR STAFF PLANNING CHART NS 137-3 DARWIN SOUTH EAST. AZIMUTHAL EQUIDISTANT PROJECTION. Used for the planning by the staff. The charts are based on a point of tangency and show radius in nautical miles. .10 TACTICAL PILOTAGE CHART. TPC R-13B. LAMBERT CONFORMAL PROJECTION. Used by pilots for flight planning and could be used in flight if necessary for visual navigation using major ground features shown on the chart. These charts also contained aeronautical information such as airfields, radio navigation beacons and obstructions. Contours and height information was shown in feet to be compatible with aircraft altimeters. Each graticule square also contained a Maximum Safe Elevation Figure (MEF) also in feet. Coverage of this series over Australia's area of interest were produced and printed at the Army Survey Regiment, Bendigo. .11 HYDROGRAPHIC CHART. AUS 158. PORT PHILLIP SOUTH and WEST CHANNELS. PROJECTION TRANSVERSE MERCATOR. Used by all people needing to navigate a vessel. Hydrographic charts were printed at the Army Survey Regiment, Bendigo. .12 HYDROGRAPHIC CHART. AUS 157. GEELONG HARBOUR and APPROACHES. PROJECTION TRANSVERSE MERCATOR. Used by all people needing to navigate a vessel. .13 EN ROUTE CHART. AUSTRALIA ERC HIGH. H1 and H2. LAMBERT CONFORMAL CONIC PROJECTION. This series of charts were regularly produced by the RAAF Aeronautical Information Service (AIS) and contained current aeronautical information for pilots. These charts were printed at the Army Survey Regiment, Bendigo..1 Tactical Pilotage Chart Series Catalogue. Current as at 30 Jun 92. .2 Extract of Navigational Plotting Chart " NP22-2 Tasmania " .3 Extract of Navigational Plotting Chart " NP 27 RAAF PLOTTING CHART AUSTRALIA - SOUTHEAST " .4 Extract of Navigational Plotting Chart " RAAF LONG RANGE PLOTTING CHART NP43-4 AUSTRALIA WESTERN " .5 Extract of Navigational Plotting Chart " RAAF LONG RANGE PLOTTING CHART NP43-7 SOLOMON ISLANDS " .6 Extract of Navigational Series " RAAF AIR STAFF PLANNING CHART NS 137-2 DARWIN NORTH WEST " .7 Extract of Navigational Series " RAAF AIR STAFF PLANNING CHART NS 137-1 DARWIN NORTH EAST " .8 Extract of Navigational Series " RAAF AIR STAFF PLANNING CHART NS 137-4 DARWIN SOUTH WEST " .9 Extract of Navigational Series " RAAF AIR STAFF PLANNING CHART NS 137-3 DARWIN SOUTH EAST " .10 Extract of Tactical Pilotage Chart " TPC R-13B " .11 Extract of Hydrographic Chart " PORT PHILLIP SOUTH and WEST CHANNELS " .12 Extract of Hydrographic Chart " GEELONG HARBOUR and APPROACHES " .13 Extract of En Route Chart " AUSTRALIA ERC HIGH " " H1 and H2 " royal australian survey corps, rasvy, fortuna, detachment - army survey regiment, army svy regt, asr

From the collection of "Maxwell Lennox Matheson" No.418447 RAAF. Enlisted 22/5/1942 Aged 19. Discharged 19/2/1948 - Rank FLTLT.This map is in colour. It is made of a stiff paper and has a map printed on both sides. Side1 - scale 1:2,315,000. 31.72 Nautical miles = 1 inch. It shows Eastern half of New Guinea. It also shows New Britain and New Ireland. Manus Island is at the top. Side 2 - Scale 1:1,000,000 - this shows Manus Island on right side, top of New Guinea at bottom edge (Wewak) and some other little islands. The map on side 1 has numerous navigation tracks and calculations in pencil. i.e. LAE, KOKODA, PORT MORESBY.ww2, raaf, new guinea

In 1941, the scientific instrument manufacturing firms of  Henry Hughes & Son Ltd, London, England, and  Kelvin Bottomley & Baird Ltd, Glasgow, Scotland, came together to form Kelvin & Hughes Ltd. Kelvin Company History: The origins of the company lie in the highly successful and strictly informal relationship between William Thomson (1824-1907), Professor of Natural Philosophy at Glasgow University from 1846-1899 and James White, a Glasgow optical maker. James White (1824-1884) founded the firm of James White, an optical instrument maker in Glasgow in 1850 and was involved in supplying and mending apparatus for Thomson university laboratory and working with him on experimental constructions. White was declared bankrupt in August 1861 and released several months later. In 1870, White was largely responsible for equipping William Thomson laboratory in the new University premises at Gilmore hill. From 1876, he was producing accurate compasses for metal ships to Thomson design during this period and this became an important part of his business in the last years of his life. He was also involved in the production of sophisticated-sounding machinery that Thomson had designed to address problems encountered laying cables at sea, helping to make possible the first transatlantic cable connection. At the same time, he continued to make a whole range of more conventional instruments such as telescopes, microscopes and surveying equipment. White's association with Thomson continued until he died. After his death, his business continued under the same name, being administered by Matthew Edwards (until 1891 when he left to set up his own company. Thomson who became Sir William Thomson and then Baron Kelvin of Largs in 1892, continued to maintain his interest in the business after James White's death. In 1884 raising most of the capital needed to construct and equip new workshops in Cambridge Street, Glasgow. At these premises, the company continued to make the compass Thomson had designed during the 1870s and to supply it in some quantity, especially to the Admiralty. At the same time, the firm became increasingly involved in the design, production and sale of electrical apparatus. In 1899, Lord Kelvin resigned from his University chair and became, in 1900, a director in the newly formed limited liability company Kelvin & James White Ltd which had acquired the business of James White. At the same time Kelvin's nephew, James Thomson Bottomley (1845-1926), joined the firm. In 1904, a London branch office was opened which by 1915 had become known as Kelvin, White & Hutton Ltd. Kelvin & James White Ltd underwent a further change of name in 1913, becoming Kelvin Bottomley & Baird Ltd. Hughes Company History: Henry Hughes & Sons were founded in 1838 in London as a maker of chronographic and scientific instruments. The firm was incorporated as “Henry Hughes & Sons Ltd” in 1903. In 1923, the company produced its first recording echo sounder and in 1935 a controlling interest in the company was acquired by S Smith & Son Ltd resulting in the development and production of marine and aircraft instruments. Following the London office's destruction in the Blitz of 1941, a collaboration was entered into with Kelvin, Bottomley & Baird Ltd resulting in the establishing “Marine Instruments Ltd”. Following the formal amalgamation of Kelvin, Bottomley & Baird Ltd and Henry Hughes & Sons Ltd in 1947 to form Kelvin & Hughes Ltd. Marine Instruments Ltd then acted as regional agents in the UK for Kelvin & Hughes Ltd who were essentially now a part of Smith's Industries Ltd founded in 1944 and the successors of S. Smith & Son Ltd. Kelvin & Hughes Ltd went on to develop various marine radar and echo sounders supplying the Ministry of Transport, and later the Ministry of Defence. The firm was liquidated in 1966 but the name was continued as Kelvin Hughes, a division of the Smiths Group. In 2002, Kelvin Hughes continues to produce and develop marine instruments for commercial and military. G. Falconer Company History: G Falconer (Hong Kong Ltd) appear to have had a retail presence in Hong Kong since 1885, according to the company website, and currently have a shop in the Peninsula Hotel. G Falconer was the Hong Kong selling agent for several British companies. Ross Ltd of 111 New Bond St London was one and the other was Kelvins Nautical Instruments. Falconers were primarily watchmakers, jewellers and diamond merchants.They were also agents for Admiralty Charts, Ross binoculars and telescopes, and sold English Silverware and High Class English Jewellery. In 1928 the company was operating from the Union Building opposite the Hong Kong general post office. It is unclear if the item is an original Sextant made by Kelvin prior to his amalgamation with Henry Hughes & Sons in 1941 as Kelvin appears to have only made compasses up to this date. If the Sextant can be established that it was made by Kelvin then it is very significant and a rare item made for and distributed through their Hong Kong selling agents G Falconer Ltd. There are many Sextants advertised for sale stating "Kelvin & Hughes 1917 model sextant". These can be regarded as replicas as the company was not formed until 1941 and production of marine instruments was not fully under way until after the war in 1947. Further investigation needs to be undertaken to accurately determine the provenance of this item. As the writer currently has the impression that the subject object was possibly made by Kelvin and Hughes in the mid to late 20th century or is a replica made by an unknown maker in the late 1970s. Purchased as an exhibition of marine navigational instruments for the Flagstaff Hill museum. The Sextant is a brass apparatus with filters and telescope lens, and comes with a wooden felt lined storage box. It is a doubly reflecting navigation instrument that measures the angular distance between two visible objects. The primary use of a sextant is to measure the angle between an astronomical object and the horizon for the purposes of celestial navigation.G Falconer and Co. Hong Kong (retailers of nautical equipmentflagstaff hill, warrnambool, shipwrecked-coast, flagstaff-hill, flagstaff-hill-maritime-museum, maritime-museum, shipwreck-coast, flagstaff-hill-maritime-village, sextant, kelvin & hughes ltd, hong kong, navigational instrument, g falconer, mariner's quadrants

A sextant is an astronomical instrument used to determine latitude and longitude at sea by measuring angular distances, especially the altitudes of the sun, moon, and stars. It is a doubly reflecting navigation instrument and used mainly by sailors to measure the angular distance between two visible objects. The name comes from the Latin sextans, or “sixth part of a unit,” because the sextant’s arc can be 60° or 120° of a circle depending on the model used. The primary use was to measure the angle between an astronomical object and the horizon for the purposes of celestial navigation. The estimation of this angle is known as sighting or shooting the object, or taking a sight. This angle and the time when it was measured is used in order to determine Greenwich Mean Time and hence longitude. Sighting the height of a landmark on land can also give a measure of distance from that object. History: The development of the sextant was as an improvement over the octant, an instrument designed to measure one's latitude. The octant was first implemented around 1731-present but can only measure angles up to 45°. As larger angles were needed to allow the measurement of lunar objects - moon, stars and the sun - at higher angles, the octant was superseded by the sextant. The sextant is a similar instrument but better made and allows larger angles from 60° to 120°. This improvement allows distances to be accurately calculated thereby giving longitude when used with a chronometer. The sextant was derived from the octant in 1757, eventually making all previous instruments used for navigational positioning obsolete. The sextant had been attributed to by John Hadley (1682–1744) and Thomas Godfrey (1704–1749), but reference to the sextant was also found later in the unpublished writings of Isaac Newton (1643–1727). Earlier links can be found to Bartholomew Gosnold (1571–1607) indicating that the use of a sextant for nautical navigation predates Hadley's implementation. In 1922, the sextant was modified for aeronautical navigation by Portuguese navigator and naval officer Gago Coutinho. It should be noted that the octant and quadrant are in the same family as they were, and all are, regarded as sextants. The sextant is representative of it's type and although not fully complete it demonstrates how 18th,19th and 20th century mariners determined their latitude and longitudinal to determine their position on a chart, allowing them to navigate there way across the world's oceans. It also demonstrates the skill and workmanship of the early instrument makers that operated scientific instrument businesses from London and other areas of England to provide most of the navigational instrumentation used by commercial and military navies of the time.Sextant with square, fitted box of polished wood, "Hezzanith" brand. Box contains many parts for the sextants use. On certificate "Heath & Co, London. Sextant Number Y 822". Catch on lid "DEFIANT LEVER" and "PATENT NUMBER 187.10". Maker's certificate is attached to the inside of the box.flagstaff hill, warrnambool, shipwrecked-coast, flagstaff-hill, flagstaff-hill-maritime-museum, maritime-museum, shipwreck-coast, flagstaff-hill-maritime-village, sextant box, sextant, hezzanith, heath & co, navigational instrument, george wilson heath, astronomical instrument, instrument manufacturers, scientific instrument, navigation, celestial navigation, octant, quadrant, lunar navigation