Telescope with Divided Glass Micrometer
date: label: date made
content: probably 1760s
label: date made
content: probably 1830s
name: label: maker
content: Dollond
notes: label: Description
content: This telescope has an achromatic objective of 2.75 inches aperture, brass tube with finder, several eyepieces, two telescoping braces, two control rods, a split objective micrometer, equatorial mount, and wooden tripod. The tube is 43.5 inches long. The faceplate at the eye end is marked “DOLLOND * LONDON.” For storage, the telescope fits into a mahogany box with a hinged lid.
label: Description
content: This seems to be an example of the brass telescope “of 3½ feet focal length, with an aperture of 2¾ inches, two eye tubes for Land Objects, and two tubes for Astronomical purposes” that George Dollond was offering in the 1830s. That instrument could be had with either a brass stand for use on a table, or “a mahogany folding stand, to be used on the Floor.” It could, moreover, be “supported in the centre of Gravity, and applied to a socket that may be turned to any latitude, so that the Telescope may have an Equatorial Motion” The complete outfit cost £50. The micrometer would be extra.
label: Description
content: The Dollond family began working as opticians in London in 1750, and gained fame in 1758 when John Dollond introduced his design for achromatic lenses. John Dollond was also responsible for the split objective micrometer.
label: Description
content: Ref: “A Description of a Contrivance for Measuring Small Angles, by Mr. John Dollond; Communicated by Mr. J. Short, F.R.S.,” <i>Philosophical Transactions of the Royal Society of London</i> 48 (1753): 178-181.
label: Description
content: “An Explanation of an Instrument for measuring small Angles, the first Account of which was read before the Royal Society May 10, 1753. By Mr. John Dollond,” <i>Philosophical Transactions of the Royal Society of London</i> 48 (1754): 551-564.
label: Description
content: George Dollond, <i>A Catalogue of Optical, Mathematical, Philosophical Instruments</i> (London, ca. 1830).
label: Description
content: Gloria Clifton, “Dollond Family,” in <i>Oxford Dictionary of National Biography</i>.
label: Location
content: Currently not on view
place: label: place made
content: United Kingdom: England, London
topic: label: Subject
content: Astronomy
setName: label: See more items in
content: Medicine and Science: Physical Sciences
label: See more items in
content: Science & Mathematics
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 1979.1110.01
label: accession number
content: 1979.1110
label: catalog number
content: 1979.1110.01
objectType: label: Object Name
content: telescope, refracting
physicalDescription: label: Physical Description
content: brass (overall material)
label: Physical Description
content: wood (overall material)
label: Measurements
content: overall: 13.5 cm x 23 cm x 116 cm; 5 5/16 in x 9 1/16 in x 45 21/32 in
label: Measurements
content: overall in case: 5 1/2 in x 9 in x 46 in; 13.97 cm x 22.86 cm x 116.84 cm