Nautical Instruments
These instruments were essential to help navigators in the calculation processes and in the practical procedures to accurately determine the position of ships at sea.
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Navigation acquired an increasingly significant scientific component and the calculation processes to determine the position of ships became more and more complex. To help navigators, instruments were created to perform measurements or to assist in the calculation processes.
Shadows Instrument - Replica
Invented by Pedro Nunes for measuring the altitude of the Sun, for the determination of latitude. Properly orientated, it indicates the altitude by the shadow of the hypotenuse of the triangle over the graduated scale. Conjectural replica.
Quadrant with "Nonius" by Pedro Nunes - Replica
Quadrant displaying the "Nonius", a theory by the Portuguese mathematician Pedro Nunes. Replica of the original made by James Kynuyn (c. 1595) displayed at the Museo Galileo, in Florence, fitted according to the drawing published by Robert Dudley in the book Dell'Arcano Del Mar.
Quadrant - Replica
Nautical instrument used at least since the early 15th century, for the determination of latitude, namely through the observation of the North Star. Initially in wood, quadrants were later made of brass or bronze.
Cross-staff - Replica (1985) by Workshops of the Maritime MuseumPortuguese Maritime Museum, a world of discoveries
Cross-staff - Replica
Nautical instrument used during the 16th and 17th centuries for measoring the altitude of the stars in the calculation of latitude.
Astronomical or Graduated Ring
Instrument invented by Pedro Nunes, for the determination of latitude using the height of the Sun.
Planispheric Astrolabe
Astronomical instrument of French origin, made by Nicol Patenal and dated 1616.
Astrolabe "Ericeira"
Nautical instrument of unknown origin, dated circa 1600. Recovered from the seabed in the vicinity of Ericeira (Portugal), in 1983.
Astrolabe "Sacramento B"
Signed by the Portuguese Agostinho Gois Raposo, made circa 1650. Recovered in 1977 from the wrecksite of the Portuguese galleon "Sacramento", sunkin 1668 in Todos os Santos Bay (Brazil). Offered by the Brazilian Navy.
Astrolabe "Santiago I"
Nautical instrument of Portuguese origin, from late 16th century. Recovered in 1980 from the wreck site of the Portuguese Indiaman "Santiago", sunk in the "shoals of Judia" (Bassas da India), Mozambique Channel in 1585.
Astrolabe "Atocha IV"
Signed by the Portuguese João Dias and dated 1614. Recovered in 1985 from the wreck site of the Spanish galleon "Nuestra Señora de Atocha", lost in 1622 off the coast of Florida.
Slide rule
Slide rule made in 1769 by António Teixeira, in Brazil, then a Portuguese colony. It was used to calculate the triangle of velocities, thus helping to determine the position of the ship.
Mariner's compass
Mariner's compass, made in Portugal by José Teixeira in 1755. This type of instrument was designed primarly to determine the variation of the compass (its error) by marking the sun at sunrise and sunset. The introduction of two removable brass pinnules enabled the reading of objects or distant aiming points.
Octant
English-made octant that belonged to the Naval Academy. It has a diagonal scale to measure degree fractions, similar to the ones used in the first octants. This instrument was invented in 1730, and allowed for the measurement of angles up to 90 degrees.
Mariner's compass (1840) by Norie & Wilson;Reys moldsPortuguese Maritime Museum, a world of discoveries
Mariner's compass
19th century mariner's compass, made in England. Before it started being used, navigators would retrieve information about different directions through some natural signals. The sailing compass contributed to a much greater accuracy as far as direction of any two points are concerned.
Telescope (c. 1801 - c. 1900) by Belonged to the Observatório Real de MarinhaPortuguese Maritime Museum, a world of discoveries
Telescope
Used until replaced by the binoculars in the 20th century. This object features a registration number 39, a lithograph with flags of various countries and a wooden case.
Quadrant with two arcs (c. 1901 - c. 2000) by António Higino de Magalhães MendonçaPortuguese Maritime Museum, a world of discoveries
Quadrant with two arcs
Also called as "Backstaff", it was used to measure the altitude of stars. It was the predecessor of the octant.
Log Glass (30 seconds) (c. 1801 - c. 1900) by W. Ludolph GmbH & CoPortuguese Maritime Museum, a world of discoveries
Log Glass (30 seconds)
Made to count 30 seconds, they were used with the log to determine the speed of the ship.
Log Glass (15 seconds)
Made to count 15 seconds, they were used with the log to determine the speed of the ship.
Terrestrial Globe
Made in England by G. Wright and W. Bardin.
Terrestrial Globe and case
18th century Globe representing Earth, with several maritime voyages represented, such as Cook's. It has a case made of two decorated semi-shperes, one featuring a map of Europe and parts of Asia and Africa and the other with the coordinates of 80 locations that are not represented in the Globe.
Compass
Dry compass with sundial. Assembled under a convex glass, within its wooden box. Made by Samuel Porter in 1824.
Proportional Dividers
Used to work out the values of trigonometrical functions, before the use of nautical tables published in books.
Equatorial Sundial
Made in England by Youle, from the 18th century.
Cubic Sundial
Of German origin, it was built by David Beringer in the second quarter of the 19th century.
Sextant
Reflecting nautical instrument, used to measure the altitude of stars above the horizon, as well as other angular distances. It was invented in 1758 by Admiral John Campbell, replacing the octant.
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