astrolabe
)
A French mariner using an astrolabe to fix the position of a star, from a vellum manuscript of Jacques Devaulx (1583; Bibliothèque Nationale, Paris, France). The mariner's astrolabe was introduced in the mid-15th century, but did not see general use until the beginning of the 16th century. It was supplanted by the sextant in the 18th century.
Ancient navigational instrument, forerunner of the sextant. Astrolabes usually consisted of a flat disc with a sighting rod that could be pivoted to point at the Sun or bright stars.
From the altitude of the Sun or star above the horizon, the local time could be estimated.
How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content.
| ?Page tools | ||
|---|---|---|
|
?Sign in  |
|---|