Hadley's Gregorian reflecting telescope, c.1740

Made:
1740-1744 in England and Cambridge
maker:
John Hadley
Hadley's Gregorian reflecting telescope, c.1740 (telescope - Gregorian; telescope - reflecting) Hadley's Gregorian reflecting telescope, c.1740 (telescope - Gregorian; telescope - reflecting) Hadley's Gregorian reflecting telescope, c.1740 (telescope - Gregorian; telescope - reflecting) Hadley's Gregorian reflecting telescope, c.1740 (telescope - Gregorian; telescope - reflecting) Hadley's Gregorian reflecting telescope, c.1740 (telescope - Gregorian; telescope - reflecting) Hadley's Gregorian reflecting telescope, c.1740 (telescope - Gregorian; telescope - reflecting) Hadley's Gregorian reflecting telescope, c.1740 (telescope - Gregorian; telescope - reflecting) Hadley's Gregorian reflecting telescope, c.1740 (telescope - Gregorian; telescope - reflecting) Hadley's Gregorian reflecting telescope, c.1740 (telescope - Gregorian; telescope - reflecting) Hadley's Gregorian reflecting telescope, c.1740 (telescope - Gregorian; telescope - reflecting)

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Science Museum Group Collection
© The Board of Trustees of the Science Museum

Science Museum Group Collection
© The Board of Trustees of the Science Museum

Science Museum Group Collection
© The Board of Trustees of the Science Museum

Science Museum Group Collection
© The Board of Trustees of the Science Museum

Science Museum Group Collection
© The Board of Trustees of the Science Museum

Science Museum Group Collection
© The Board of Trustees of the Science Museum

Science Museum Group Collection
© The Board of Trustees of the Science Museum

Science Museum Group Collection
© The Board of Trustees of the Science Museum

Science Museum Group Collection
© The Board of Trustees of the Science Museum

Science Museum Group Collection
© The Board of Trustees of the Science Museum

Gregorian reflecting telescope, said to have made by John Hadley in 1726, although stylistic features would suggest a later date of c.1740. The telescope has a 2-inch metal speculum mirror with a focal length of 14 inches and a sharkskin covered brass tube with metal case.

Dated 1724, this telescope has been described as the earliest example of a reflecting telescope using the Gregorian optical configuration. The Scottish mathematician, James Gregory first suggested this optical layout in 1663. Yet he was unable to have it made due the difficulty of making mirrors with non-spherical surfaces. Over fifty years later, Hadley succeeded where Gregory failed, after making a reflecting telescope using Isaac Newton's principles in 1721. He presented his Newtonian Telescope to the Royal Society of London who found it performed favourable with the best of telescopes then available. Although having remained in the Hadley family until the nineteenth century, it seems likely, from style and design, that this Gregorian telescope was made later around 1740.

Details

Category:
Astronomy
Object Number:
1937-601
Materials:
complete, brass (copper, zinc alloy), fishskin, speculum (alloy of copper and tin) and glass
Measurements:
overall: 80 x 80 x 370 mm
type:
telescope - gregorian and telescope - reflecting
credit:
Cambridge Observatory

Parts

Case for the first Gregorian reflecting telescope

Case for the first Gregorian reflecting telescope

Metal case for the first Gregorian reflecting telescope which was made by John Hadley in 1726.

Measurements:
overall: 300 x 80 x 90 mm
Materials:
iron
Object Number:
1937-601 Pt1
type:
components , storage boxes and instruments