A burning glass or burning lens is a large convex lens that can concentrate the sun's rays onto a small area, heating up the area and thus resulting in ignition of the exposed surface. Burning mirrors achieve a similar effect by using reflecting surfaces to focus the light. They were used in 18th-century chemical studies for burning materials in closed glass vessels where the products of combustion could be trapped for analysis. The burning glass was a useful contrivance in the days before electrical ignition was easily achieved.
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Famous quotes containing the words burning and/or glass:
“The host is rushing ‘twixt night and day,
And where is there hope or deed as fair?
Caoilte tossing his burning hair,
And Niamh calling Away, come away.”
—William Butler Yeats (1865–1939)
“More Safe, and much more modest ‘tis, to say
God wou’d not leave Mankind without a way:
And that the Scriptures, though not every where
Free from Corruption, or intire, or clear,
Are uncorrupt, sufficient, clear, intire,
In all things which our needfull Faith require.
If others in the same Glass better see
‘Tis for Themselves they look, but not for me:
For MY Salvation must its Doom receive
Not from what OTHERS, but what I believe.”
—John Dryden (1631–1700)