speculum metal

American  

noun

1. any of several bronze alloys with a high tin content, often containing other materials, as silver, brass, lead, zinc, or arsenic, used for making mirrors and reflectors.

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speculum metal British  

noun

1. a white hard brittle corrosion-resistant alloy of copper (55–70 per cent) and tin with smaller amounts of other metals. It takes a high polish and is used for mirrors, lamp reflectors, ornamental ware, etc

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Etymology

Origin of speculum metal

First recorded in 1790–1800

Example Sentences

See Examples For:

speculum metal

For speculum metal when cold is excessively brittle, and were the casting permitted to cool like an ordinary copper or iron casting, the mirror would inevitably fly into pieces.

From Great Astronomers by Sir Robert S. (Robert Stawell) Ball

When completed, the disc of speculum metal was about six feet across and four inches thick.

From Great Astronomers by Sir Robert S. (Robert Stawell) Ball

A reflecting telescope of the present day would not be fitted with a mirror composed of that alloy known as speculum metal, whose composition I have already mentioned.

From Great Astronomers by Sir Robert S. (Robert Stawell) Ball

The great reflectors of Herschel and Lord Rosse, which were provided with mirrors of speculum metal, were far inferior to much smaller telescopes of the present day.

From The New Heavens by George Ellery Hale

The above process may be employed for speculum metal, or pitch may be used.

From On Laboratory Arts by Richard Threlfall