2.75-foot Gregorian reflecting telescope
Date1733-1763
Inventory NumberDW0814
ClassificationTelescope
Subject
Maker
Jean-Baptiste-Charles Gonichon
fl. 1733 - 1763
Cultural Region
Place of Origin
Dimensionswith telescope horizontal: 66 x 42.5 x 100 cm (26 x 16 3/4 x 39 3/8 in.)
Material
Accessoriesdust covers for tube and eyepiece
DescriptionThis Gregorian reflecting telescope has a primary mirror of approximately 12 cm diameter. It is cast of speculum metal. The rear of the casting is stamped twice with a deep G.
The eyepiece has a very tiny aperture stop. A dust cover is screwed over the end. It is dot marked with 4 dots and the numeral "4." Four dots appear also on two segments of the eyepiece barrel.
The focusing screw is of short length external to the tube. Most of the focusing arm is internal.
The secondary mirror is present. The focal length is approximately 32-33 inches. The aperture is about 5 inches.
There is a sighting telescope attached to the main tube by means of circular collars on screw brackets.
The tube is attached to the altazimuth mount by means of two screws that hold it to a pair of padded, slotted saddles. The saddles are mounted on an ornamental semicircle pierced with scrolling foliage. The semicircle pivots on a fork with a locking screw with a butterfly head. At the base of the fork is a curved strap with two guide screws that rub against the limb of the semicircle. The fork rotates on top of a turned pillar. The pillar is set onto a round base. The base rests on three folding cabriole legs with scroll feet.
The eyepiece has a very tiny aperture stop. A dust cover is screwed over the end. It is dot marked with 4 dots and the numeral "4." Four dots appear also on two segments of the eyepiece barrel.
The focusing screw is of short length external to the tube. Most of the focusing arm is internal.
The secondary mirror is present. The focal length is approximately 32-33 inches. The aperture is about 5 inches.
There is a sighting telescope attached to the main tube by means of circular collars on screw brackets.
The tube is attached to the altazimuth mount by means of two screws that hold it to a pair of padded, slotted saddles. The saddles are mounted on an ornamental semicircle pierced with scrolling foliage. The semicircle pivots on a fork with a locking screw with a butterfly head. At the base of the fork is a curved strap with two guide screws that rub against the limb of the semicircle. The fork rotates on top of a turned pillar. The pillar is set onto a round base. The base rests on three folding cabriole legs with scroll feet.
Signedon tailpiece: Gonichon Opticien rue des Postes / Paris
cast twice into rear of primary mirror: G
Inscribedon eyepiece dust cover: 4
ProvenanceDavid Wheatland purchased from Alain Brieux, Paris, February 20, 1962 (lot 2/2).
Alvan Clark and Sons
Date: 1910
Accessories: shipping crate, terrestrial eyepiece, dust cap, mount and tripod (2003-1-0077b)
Object number: 2003-1-0077a
Gaspard Rochette
Date: circa 1785
Accessories: dust cap for eyepiece and tube
Object number: DW0164
Claude-Siméon Passemant
Date: 1750-1769
Accessories: dust cap
Object number: DW0936
W. & S. Jones
Date: circa 1839
Accessories: 4 eyepieces; case
Object number: 1996-1-0001
R. & J. Beck
Date: 1876
Accessories: oculars (2) in microscope; Darker's selenite retarding filters (3); wheel diaphragm; mechanical rotary stage; stage slider. Other accessories are in the case (1122b), including monocular draw tube; oculars (3); objectives in cans (5); empty can; Lieberkühn; polarizing set; slides; camera lucidas (2); etc.; plus a Beck patent substage condenser (1122c); and apertometer (1122d).
Object number: 1122a
James Short
Date: circa 1763
Accessories: split object glass micrometer; spare secondary mirror in tin box (0002b).
Object number: 0002
English
Date: 1715-1720
Accessories: solar filter; lens; awl; dust caps.
Object number: 5002
Bausch & Lomb Optical Company
Date: circa 1877
Accessories: B&L objectives (2); 1 ocular; camera lucida; eyepiece micrometer; slides (12 prepared; 2 plain); glass pipette; box of cover glasses; directions card; magnification card; case with key
Object number: 1056