Mirrors of speculum metal were hard to produce and were only owned by the wealthy.
Speculum metal is an alloy of around two-thirds copper and one-third tin.
A small portion of speculum metal, when analysed, yielded iron.
Speculum metal and brass cannot be soldered together by the ordinary methods.
Speculum metal was very hard to cast and shape.
He chose an alloy (speculum metal) of tin and copper as the most suitable material for his objective mirror.
For nearly 200 years speculum metal was the only mirror substance that could perform this task.
After much experiment, he chose an alloy (speculum metal) of tin and copper as the most suitable material for his objective mirror.
