But speculum metal is a material of a very intractable description.
Furnaces for the speculum metal were built, stands erected, and the 40-foot telescope fairly begun.
The above process may be employed for speculum metal, or pitch may be used.
The specula are made of speculum metal, which is a composition of certain proportions of copper and tin.
When completed, the disc of speculum metal was about six feet across and four inches thick.
They are made of speculum metal, of various forms and sizes, but always portable.
Third: Clear water takes no shadow, and that for two reasons; A perfect surface of speculum metal takes no shadow, 8.