|
Date: |
|
Description: | LO 115 (departmental catalogue number in aluminium paint). Troughton London. Silver 1048 (engraved on the scale) 0-140 + (scale divisions of 10 seconds engraved on silver scale). 0-10 ( vernier scale divisions engraved in silver). Baker (written in pencil inside the lid). MANU Troughton circa 1800 The sign of the orrery,136 Fleet Street, London, England DES TROUGHTON,Edward 1788 136, Fleet Street, London, England. DES after WRIGHT, George or Thomas before 1780 DES after BIRD,John. 1757 London, England. The sextant was introduced circa 1760 after the introduction of the lunar distance method in 1757 which required greater accuracy than the quadrant could achieve. The quintant is a 144 degree arc version of the sextant and was used as hydrographic surveying instrument. In modern usage all instruments of this type regardless of the size of scale are called sextants. This eleven and a half inch instrument, with a combination of seven shades; two green, four red and a magenta, has a 200mm radius scale and can be read to 1 sec. The index arm which is reinforced has a venier microscope and a tangent screw clamp. The oxidised brass pillar frame has two straight struts. There are three interchangeable backsights; a pin hole, a terestial, and an astronomical which has two draw tubes. N.B. the forsight mirror is adjustabl using the screw adjuster stored in the side slot in the box. As in Hadley's quadrant the mirror halves the scale. | License: | http://www.hmag.gla.ac.uk/spirit/rights/ | Publisher: | Hunterian Museum and Art Gallery, University of Glasgow | Rights holder: | Hunterian Museum and Art Gallery, University of Glasgow | Subjects: | SCIENTIFIC COLLECTION : | Source: | Hunterian Museum | Creator: | Hunterian Museum and Art Gallery, University of Glasgow | Identifier: | http://www.huntsearch.gla.ac.uk/cgi-bin/... | Language: | en-GB | Go to resource |
|
More Like this...
-
Quintant
National Physical Laboratory, KEW OBSERVATORY,…
-
Sextant
LO 114 (departmental catalogue number…
-
-
-
Sextant
?2076?
?E. Smith, from Whitbreads,…
-
-
-
-
Sextant
The sextant has a polished…
-
Sextant
Invented & Made by Troughton…
|