What is Periscope?
[[File:British trench periscope Cape Helles 1915.jpg|thumb|British soldier in [[World War I]] using a periscope to see from a [[trench]]]] [[File:Periscope simple.svg|thumb|Design of a persicope. The model on the left uses mirrors, the one on the right uses prisms]] A '''periscope''' is an [[Optics|optical]] instrument that is used to watch a scene from cover. The classical design uses a number of [[Mirror|mirrors]] or [[Prism (optics)|prisms]], and is used in [[Tank|tanks]] and [[Submarine|submarines]]. [[Category:Optical devices]] [[Category:Tools]]