Octant
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Description
The octant (eighth part of the circle) marked the first evolution in the design of the quadrant as a basic navigational instrument. It measures the altitude of the Sun and other celestial bodies above the horizon. From this datum, one can determine the latitude using numerical tables. The instrument consisted of an eighth of a circle divided into 45° and fitted with sighting optics. It was also used on land to find the distance between two points. In the late eighteenth century, the octant was replaced on ships by the sextant (sixth of a circle), whose 60° arc afforded a wider field of view.
Bibliographical Resources
Hofmann, Heinrich. De octantis instrumenti mathematici novi geodaetis, astronomis, geographis, nautis, architectis, militibus & fodinarum praefectis perquam utilis & accomodati usu & utilitate libellus / ab authore Henrico Hofmanno ... conscriptus ac boni publici caussâ in lucem datus. Jenae, typis haeredum Lippoldianorum, 1612.
Existing Instruments
- Museo Galileo, Institute and Museum of the History of Science, Florence
Florence, Museo Galileo. Institute and Museum of the History of Science, inv. 120.
Florence, Museo Galileo. Institute and Museum of the History of Science, inv. 707.
- The Science Museum, London
The Science museum, inv. 1872-77
- Museum of the History of Science, Oxford
Museum of the History of Science, Oxford, inv. 34460
Museum of the History of Science, Oxford, inv. 38825
Museum of the History of Science, Oxford, inv. 49029
Museum of the History of Science, Oxford, inv. 48059
Museum of the History of Science, Oxford, inv. 40993
Museum of the History of Science, Oxford, inv. 41654
Museum of the History of Science, Oxford, inv. 40202
Museum of the History of Science, Oxford, inv. 52739
Museum of the History of Science, Oxford, inv. 52728
Museum of the History of Science, Oxford, inv. 33700
Museum of the History of Science, Oxford, inv. 33576
Museum of the History of Science, Oxford, inv. 54812
Museum of the History of Science, Oxford, inv. 44939
Museum of the History of Science, Oxford, inv. 39479
Museum of the History of Science, Oxford, inv. 53981
Museum of the History of Science, Oxford, inv. 12959
Museum of the History of Science, Oxford, inv. 54686
Museum of the History of Science, Oxford, inv. 40933
Links (External)
http://www.bncf.firenze.sbn.it/notizie/Cartografia%20Web/Strumenti/Ottante.htm (Italian)
http://visite.artsetmetiers.free.fr/instruments.html (French)
Images
 Heinrich Hofmann. De octantis. Jenae, 1612, c. B. |
 Heinrich Hofmann. De octantis. Jenae, 1612, c. C2. |
 Heinrich Hofmann. De octantis. Jenae, 1612. |
