plate holder for 8-inch photographic telescope
Date: 1880-1890
Inventory Number: 1996-1-0471
Classification: Photographic Plate Holder
Subject:
Maker: American
Supplier: Alvan Clark and Sons ? (1846 - 1958)
Maker: Boyden Station, Arequipa (1891 - 1927)
Maker: Boyden Station, Bloemfontein (founded 1927)
Maker: Harvard College Observatory (founded 1839)
Maker: George R. Agassiz Station, Harvard (1951 - 1982)
Cultural Region:
Place of Origin:
Dimensions:
32.3 × 34.3 × 5.5 cm (12 11/16 × 13 1/2 × 2 3/16 in.)
box: 10.6 × 39.5 × 36.5 cm (4 3/16 × 15 9/16 × 14 3/8 in.)
DescriptionThis is a plate holder designed to attach to a telescope with an 8-inch aperture. It is formed of three flat, dasmacened red-brass plates (A, B, C) adjustable at right angles to each other plus a mahogany frame for the photographic glass plate. It is also provided with an adjustable cross hairs and eyepiece.
The rear plate (A) of the plate holder has a raised collar that would be inserted into the end of the photographic telescope and serve as its tailpiece. The aperture of the collar (inner diameter) is 8 11/32 inches (21.3 cm) but it has been squared off to create an opening of 7.75 x 7.75 inches. The outer diameter of the collar is 8 3/4 inches (22.2 cm). There are 4 horizontal screws for tightening the plate holder assembly to the telescope tube. The rear of the plate is damascened.
This plate (A) has a track in which plate B moves by means of a large knurled screw. This second plate (B) is attached to another plate (C) that carries the frame for the photographic plate. This C plate is adjusted with respect to the B plate below by means of another large knurled screw. A pair of binding posts are mounted adjacent to the screw.
The frame for the glass plate has brass sides, latches, and hinges with a mahogany door. The metal is silvered. There is a silvered clamping lever on the hinge side of the door. The shutter slide is made of aluminum. A pull knob releases it and permits it to be retracted or slid into place. The glass plates to be used would be about 6.5 x 6.5 inches.
Along side the plate frame there is a metal trough with a glass top. A precision screw within the trough moves a metal bracket longitudinally down the trough. This bracket has a small lens with cross hairs. It's motion is operated by a knurled thumbscrew outside of the trough. The other end of the trough has a brass column in which a light would have been inserted for illumination of the cross hairs. The light is missing and its electrical connectors.
An eyepiece (missing) is mounted on a slider that moves in a track above the glass on the trough.
The instrument has a fitted mahogany box lined in places with green felt. The box has brass hardware including a handle on the side, a lock, and latch hooks. The lid is split and separated from the box bottom.
Various accessories to the plate holder are missing.
The rear plate (A) of the plate holder has a raised collar that would be inserted into the end of the photographic telescope and serve as its tailpiece. The aperture of the collar (inner diameter) is 8 11/32 inches (21.3 cm) but it has been squared off to create an opening of 7.75 x 7.75 inches. The outer diameter of the collar is 8 3/4 inches (22.2 cm). There are 4 horizontal screws for tightening the plate holder assembly to the telescope tube. The rear of the plate is damascened.
This plate (A) has a track in which plate B moves by means of a large knurled screw. This second plate (B) is attached to another plate (C) that carries the frame for the photographic plate. This C plate is adjusted with respect to the B plate below by means of another large knurled screw. A pair of binding posts are mounted adjacent to the screw.
The frame for the glass plate has brass sides, latches, and hinges with a mahogany door. The metal is silvered. There is a silvered clamping lever on the hinge side of the door. The shutter slide is made of aluminum. A pull knob releases it and permits it to be retracted or slid into place. The glass plates to be used would be about 6.5 x 6.5 inches.
Along side the plate frame there is a metal trough with a glass top. A precision screw within the trough moves a metal bracket longitudinally down the trough. This bracket has a small lens with cross hairs. It's motion is operated by a knurled thumbscrew outside of the trough. The other end of the trough has a brass column in which a light would have been inserted for illumination of the cross hairs. The light is missing and its electrical connectors.
An eyepiece (missing) is mounted on a slider that moves in a track above the glass on the trough.
The instrument has a fitted mahogany box lined in places with green felt. The box has brass hardware including a handle on the side, a lock, and latch hooks. The lid is split and separated from the box bottom.
Various accessories to the plate holder are missing.
In Collection(s)
Signedunsigned
Historical AttributesUsed by Harvard College Observatory on an 8-inch photographic telescope, possibly the Bache telescope (1885), the Boyden telescope (1887), or the Draper telescope (1889). These instruments traveled to Harvard's field stations in Peru and South Africa. All were made by Alvan Clark & Sons, who may have been involved in assembling this plate holder to fit their telescopes. The parts, however, especially the damascened brass, were likely made by a subcontractor.
ProvenanceHarvard College Observatory; likely transfer to CHSI in 1969 from Agassiz Station.