File:ReflectingTelescope 017.jpg

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Summary

Description

Largest disk of optical glass created in the United States as of 1928. The mold for this disk was specifically designed for this purpose and was at the same time a carefully insulated annealing furnace provided with electrical heating elements for controlling the temperatures during cooling. The glass was poured at 2400 degrees Fahrenheit. Eight months were required for cooling and annealing. The disk weighed about 4,000 pounds, was 11 inches thick, and made from borosilicate crown glass. It was intended for use at the Perkins Observatory of Delaware, Ohio.

Source

National Institute of Standards and Technology

Author

National Institute of Standards and Technology

Permission
(Reusing this file)

This image is in the public domain in the United States because it is a work of the United States Federal Government, specifically an employee of the National Institute of Standards and Technology, under the terms of Title 17, Chapter 1, Section 105 of the US Code.

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Licensing

This image is in the public domain in the United States because it is a work of the United States Federal Government, specifically an employee of the National Institute of Standards and Technology, under the terms of Title 17, Chapter 1, Section 105 of the US Code.

English ∙ 日本語 ∙ македонски ∙ Nederlands ∙ +/−

File history

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	Date/Time	Thumbnail	Dimensions	User	Comment
current	18:04, 10 March 2014		5,738 × 4,644 (25 MB)	NISTResearchLibrary

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Metadata

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Image title	Largest disk of optical glass created in the United States as of 1928. The mold for this disk was specifically designed for this purpose and was at the same time a carefully insulated annealing furnace provided with electrical heating elements for controlling the temperatures during cooling. The glass was poured at 2400 degrees Fahrenheit. Eight months were required for cooling and annealing. The disk weighed about 4,000 pounds, was 11 inches thick, and made from borosilicate crown glass. It was intended for use at the Perkins Observatory of Delaware, Ohio.
Author	National Institute of Standards and Technology
Copyright holder	The images in the Reflecting Telescope Photographic Collection are in the public domain and are not subject to copyright in the United States. However, please pay special attention to the individual works to make sure there are no copyright restrictions indicated. Individual works may require securing other permissions from the original copyright holder. Use of the images from NIST Digital Collections is not restricted, but a statement of attribution is required. Please use the following attribution statement: "National Institute of Standards and Technology Digital Collections, Gaithersburg, MD 20899."
Headline	National Institute of Standards and Technology
Source	Reflecting Telescope Photographic Collection
Short title	Perkins Observatory director Prof. Clifford C. Crump [left] and NBS director George K. Burgess pictured [right] with the 70-inch optical glass disk with an 8-inch hole drilled in its center for mounting
Width	5,738 px
Height	4,644 px
Bits per component	16 16 16
Compression scheme	Uncompressed
Pixel composition	RGB
Orientation	Normal
Number of components	3
Horizontal resolution	600 dpi
Vertical resolution	600 dpi
Data arrangement	chunky format
Software used	Adobe Photoshop CS6 (Windows)
File change date and time	16:40, 17 September 2013
Exif version	2.21
Color space	Uncalibrated
Unique ID of original document	643C5A16131D8AD83B9D7426BEED6CC1
Date metadata was last modified	12:40, 17 September 2013
Date and time of digitizing	06:02, 17 July 2013
Keywords	United States. National Bureau of Standards--Photograph collections. Optical glass--Photograph collections. Reflecting telescopes--Photograph collections.
Contact information	library@nist.gov 100 Bureau Dr, MS 2500 Gaithersburg, MD, 20899 301-975-3052
IIM version	4