
Periscope
Naval Device
Periscope is primarily associated with nautical use, especially in submarines for observation.

The captain ordered, 'Extend the periscope,' to survey the horizon.
Vertical Mobility
Periscopes can move up or down to provide a safe way to observe without being exposed.

The sailor raised the periscope carefully to remain undetected.
Visibility Aid
Periscopes are useful when direct line of sight is blocked, allowing indirect viewing.

They used the periscope to view the landscape beyond the wall.
Compare with
SpyglassTelescope
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