burning glass

American  

noun

1. a converging lens used to produce heat or ignite substances by focusing the sun's rays.

---

burning glass British  

noun

1. a convex lens for concentrating the sun's rays into a small area to produce heat or fire

---

Etymology

Origin of burning glass

First recorded in 1560–70

Example Sentences

He and I know to move around them by sheer memory; the burning glass promises to singe the skin if touched.

From The Guardian • Apr. 17, 2018

Priestley did not know what he had made when he heated red oxide of mercury with a burning glass and collected the atmosphere caused by the process.

From Time Magazine Archive

Suddenly the public gaze converged on them like sunlight through a burning glass, and their names blazed into lights.

From Time Magazine Archive

The film begins with a helicoptic view, swooping over the dome of St. Peter's, then briefly darts away to Greece to catch the sun's rays igniting the traditional torch through a burning glass at Olympia.

From Time Magazine Archive

The sun's rays scattered do no execution, but concentrated in a burning glass, they melt solid granite; yes, a diamond, even.

From How to Succeed or, Stepping-Stones to Fame and Fortune by Marden, Orison Swett