astronomical quadrant with achromatic sights
Date: 1765
Inventory Number: 0061
Classification: Astronomical quadrant
Subject:
Maker: Jeremiah Sisson (1720 - 1783)
Supplier: Benjamin Franklin (1706 - 1790)
User: John Winthrop (1714 - 1779)
User: Samuel Williams (1743 - 1817)
Repaired by: W. & S. Jones (fl. 1791 - 1859)
Cultural Region:
Place of Origin:
City of Use:
Dimensions:
188 x 68 x 76 cm (74 x 26 3/4 x 29 15/16 in.)
fixed horizontal telescope: 55.9 cm (22 in.)
radius of quadrant: 61 cm (24 in.)
Bibliography:
The Apparatus of Science at Harvard, 1765-1800
DescriptionThis brass quadrant has telescopic sights. One telescope is fastened on the upper horizontal brace. The second moves with the index arm. It has four transit lines in the field of view. The telescopes are early achromats.
The index arm is fitted with a clamp, fine adjustment screw, and two verniers. There are two parallel scales on the limb. One is marked 5°-0°-90°-85°, every 10', with a vernier giving divisions to 1'. The other scale is unlabeled, but also divided to 10' and has its own vernier. It may be William and Samuel Jones's new divisions from 1817.
A level is fastened to a horizontal cross brace.
The quadrant turns on a steel shaft that extends through the stand into a brass sleeve in the base. The pointed end of the shaft allows the instrument to turn freely.
The stand consists of a colonnade of 8 pillars resting on a horizontal platform formed by four beams at right angles. This base is currently mounted on 19th century casters.
The top of the stand has a brass azimuth scale, divided 0°-90°-0°-90°-0°, with subdivisions to 30' and vernier reading to 1' of arc.
The index arm is fitted with a clamp, fine adjustment screw, and two verniers. There are two parallel scales on the limb. One is marked 5°-0°-90°-85°, every 10', with a vernier giving divisions to 1'. The other scale is unlabeled, but also divided to 10' and has its own vernier. It may be William and Samuel Jones's new divisions from 1817.
A level is fastened to a horizontal cross brace.
The quadrant turns on a steel shaft that extends through the stand into a brass sleeve in the base. The pointed end of the shaft allows the instrument to turn freely.
The stand consists of a colonnade of 8 pillars resting on a horizontal platform formed by four beams at right angles. This base is currently mounted on 19th century casters.
The top of the stand has a brass azimuth scale, divided 0°-90°-0°-90°-0°, with subdivisions to 30' and vernier reading to 1' of arc.
In Collection(s)
Signedon limb: J. Sisson London
FunctionThe primary function of the astronomical quadrant is to measure the altitude of a celestial body in terms of angle. In this form, itt is also a tool for geodetic surveying, because it can be used to measure angles of elevation and azimuth with precision for either celestial or terrestrial objects.
Historical AttributesThe first shipment of apparatus sent from London in 1765 to replace that lost in the fire included "An Astronomical Quadt: of 2 feet Radius (made by Sisson) with Steel Spindle, Azimuth Circles, with Nonies...Mahogany pedestal. The Quadt: by help of a Nonies division to every 30 Second, & a Micrometer to 5." Harvard paid £59.17.0 for it. It was selected with the help of Benjamin Franklin.
In 1769, John Winthrop, Hollis Professor of Mathematics and Natural Philosophy, used the astronomical quadrant to observe the Transit of Venus from Cambridge.
In October 1780, Winthrop's successor, Professor Samuel Williams, and several students took the astronomical quadrant behind enemy lines during the American Revolution in order to observe a total solar eclipse on Long Island in Penobscot Bay, Maine. (He also took two Short reflectors, 0053 and 0002, Ellicott clock, 0070, and most likely the Nairne azimuth compass, 0095, Martin octant, 0007, and Martin surveyor's level, 0068.) The expedition was endorsed by Harvard and the American Academy of Arts and Sciences, and sponsored by the General Court of Massachusetts. Reports of the expedition describe the telescope on the quadrant as being an achromat of 2 1/2 foot.
In March 1817, W. and S. Jones charged the College £15.13.0 for work "Repairing and cleaning all the brass work and newly "dividing the limb" on Sisson's quadrant. The College protested the high fee, and in return received a letter from William Jones stating:
"We applied no more work, or made other additions, than we were allowed by Professor Farrar's distinct and proper written directions so to do. Indeed, we avoided considerable work or expense respecting the Quadrant, as that Gentlem. directed the frame work to be cleaned and lacquered, which if done, the bars must have been separated, and the instrument new framed; and expence of many pounds more. This we superceeded by painting. Now Sir, these particularly nice Instruments can only be repaired by our very best, and most competent workmen, artists, who have treble wages of the ordinary sort. They must be well done or not done at all."
In 1769, John Winthrop, Hollis Professor of Mathematics and Natural Philosophy, used the astronomical quadrant to observe the Transit of Venus from Cambridge.
In October 1780, Winthrop's successor, Professor Samuel Williams, and several students took the astronomical quadrant behind enemy lines during the American Revolution in order to observe a total solar eclipse on Long Island in Penobscot Bay, Maine. (He also took two Short reflectors, 0053 and 0002, Ellicott clock, 0070, and most likely the Nairne azimuth compass, 0095, Martin octant, 0007, and Martin surveyor's level, 0068.) The expedition was endorsed by Harvard and the American Academy of Arts and Sciences, and sponsored by the General Court of Massachusetts. Reports of the expedition describe the telescope on the quadrant as being an achromat of 2 1/2 foot.
In March 1817, W. and S. Jones charged the College £15.13.0 for work "Repairing and cleaning all the brass work and newly "dividing the limb" on Sisson's quadrant. The College protested the high fee, and in return received a letter from William Jones stating:
"We applied no more work, or made other additions, than we were allowed by Professor Farrar's distinct and proper written directions so to do. Indeed, we avoided considerable work or expense respecting the Quadrant, as that Gentlem. directed the frame work to be cleaned and lacquered, which if done, the bars must have been separated, and the instrument new framed; and expence of many pounds more. This we superceeded by painting. Now Sir, these particularly nice Instruments can only be repaired by our very best, and most competent workmen, artists, who have treble wages of the ordinary sort. They must be well done or not done at all."
Primary SourcesSamuel Williams, "Observations of a solar eclipse, October 27, 1780, made on the east side of Long-Island, in Penobscot-Bay," Memoirs of the American Academy of Arts and Sciences 1 (1785): 86-102.
Published ReferencesDavid P. Wheatland, The Apparatus of Science at Harvard, 1765-1800 (Cambridge: Harvard University Press, 1968), 34-37, 43.