Noun
burning glass (plural burning glasses)
A large convex lens or concave mirror that can concentrate the sun's rays onto a small area, heating up the area and thus resulting in ignition of the exposed surface.
Synonym: burning lens
burning-glass (plural burning-glasses)
(dated) A magnifying lens, as used to focus sunlight on to an object.
burning-glass
A shaft of fire that falls like dew, And melts and maddens all my blood, From out thy spirit flashes through The burning glass of womanhood. George William Russell
In October the English chemist Joseph Priestley visited Paris, where he met Lavoisier and told him of the air which he had produced by heating the red calx of mercury with a burning glass and which had supported combustion with extreme vigor. Source: Internet
The burning glass was a useful contrivance in the days before electrical ignition was easily achieved. Source: Internet
History The technology of the burning glass has been known since antiquity. Source: Internet