astronomical transit
Date: 1851-1880
Inventory Number: 1989-4-0002a
Classification: Transit
Subject:
Maker: Stackpole and Brother (1851 - 1910)
User: Harvard College Observatory (founded 1839)
User: Boyden Station, Arequipa (1891 - 1927)
User: George R. Agassiz Station, Harvard (1951 - 1982)
Cultural Region:
Place of Origin:
Dimensions:
overall with telescope level: 66 × 41 × 75.5 cm (26 × 16 1/8 × 29 3/4 in.)
telescope tube length: 75.5 cm (29 3/4 in.)
cast iron stand height: 65 cm (25 9/16 in.)
Accessories: pine storage box
Description:
This is a portable astronomical transit made of brass. It has a striding level and dust cap for the telescope lens. There is a graduated circle and a clamp. The telescope aperture is 2 inches.
The conical trunions are adjustable in height, with a dial on the side of the frame. They have open optics down the axis for collimation. On the right there is a tangent screw and clamp with an adjusting level. On the left there is a vertical setting circle. It is silvered with verniers, a level, and two reading lenses. It is divided 0-360 degrees every 30 minutes (1/2 degree). The vernier reads to 1 minute of arc. There is a clip for a light.
The instrument has leveling screw feet. The eyepiece is set at a right angle.
For a description of the mounting, please see 1989-4-0002b.
The conical trunions are adjustable in height, with a dial on the side of the frame. They have open optics down the axis for collimation. On the right there is a tangent screw and clamp with an adjusting level. On the left there is a vertical setting circle. It is silvered with verniers, a level, and two reading lenses. It is divided 0-360 degrees every 30 minutes (1/2 degree). The vernier reads to 1 minute of arc. There is a clip for a light.
The instrument has leveling screw feet. The eyepiece is set at a right angle.
For a description of the mounting, please see 1989-4-0002b.
In Collection(s)
Signedon axis: STACKPOLE & BROTHER / NEW YORK
Inscribedserial number on axis: 1598
FunctionAn astronomical transit is used with a clock to measure the altitude and time that a star or celestial body crosses the meridian at a specific location. This gives the declination and right ascension of the star, which are that star's coordinates in the sky. The information can also be used to find the longitude of a location if one has knowledge of when the meridian crossing would happen at the zeroth longitude.
If one has a table listing when a particular star is to cross the meridian at a given location, one can use the transit to find the time at that location at that moment. For this reason, small table top transits were often used by watchmakers to check the running of their watches and clocks.
Medium-sized and larger portable transits (like this one) were used in the field by astronomers when they went on expeditions to observe an eclipse or Transit of Venus.
If one has a table listing when a particular star is to cross the meridian at a given location, one can use the transit to find the time at that location at that moment. For this reason, small table top transits were often used by watchmakers to check the running of their watches and clocks.
Medium-sized and larger portable transits (like this one) were used in the field by astronomers when they went on expeditions to observe an eclipse or Transit of Venus.
Historical AttributesUsed as a student transit and portable transit by Harvard College Observatory. It was in Arequipa, Peru at the Observatory's Boyden Station in the late 19th century, and was later collected from the Agassiz Station, near Harvard, Mass. in 1969.
Curatorial RemarksThe storage case for the telescope portion of the transit is catalogued separately as 1989-4-0002c.
The mounting is catalogued separately from the tube assembly, because each had their own boxes. The mounting is 1989-4-0002b.
The mounting is catalogued separately from the tube assembly, because each had their own boxes. The mounting is 1989-4-0002b.
ProvenanceHarvard College Observatory; transfer from Agassiz Station to CHSI, 1969.
