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

The combination acts as a gigantic burning glass which can melt 130 Ibs. of iron in an hour.

From Time Magazine Archive

Secondly, was his 'into battle' period, when his superb rhetoric and unflinching courage focused like a burning glass the latent will to win of heroic, freedom-loving men the world over, when all seemed lost.

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

Endeavouring by kind looks and gestures to soothe their perturbation, Captain Clark held up a burning glass to catch a stray sunbeam with which to light his pipe.

From The Columbia River Its History, Its Myths, Its Scenery, Its Commerce by Lyman, William Denison