Periscope

Australian Light Horse troops using a periscope rifle, Gallipoli, 1915. Photograph by Ernest Brooks.

A team of German artillery observers using periscope binoculars, 1943

A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position.

In its simplest form, it consists of an outer case with mirrors at each end set parallel to each other at a 45-degree angle. This form of periscope, with the addition of two simple lenses, served for observation purposes in the trenches during World War I. Military personnel also use periscopes in some gun turrets and in armoured vehicles.

单词	Periscope depth
释义	Periscope depth 英语百科 Periscope A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position. In its simplest form, it consists of an outer case with mirrors at each end set parallel to each other at a 45-degree angle. This form of periscope, with the addition of two simple lenses, served for observation purposes in the trenches during World War I. Military personnel also use periscopes in some gun turrets and in armoured vehicles.
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Periscope depth

Periscope