Periscope

A periscope is an instrument for observation from a concealed position. In its simplest form it is a tube in each end of which are mirrors set parallel to each other and at an angle of 45° with respect to the line between them. It may be used as a toy or for seeing over people's heads in a crowd. This form of periscope, with the addition of a simple lens, was used for observation purposes in the trenches during World War I. More complex periscopes, using prisms instead of mirrors, and providing magnification, are used on submarines.

Related Topics:
Mirror - Toy - World War I - Prism - Submarine

~ ~ ~ ~ ~ ~ ~ ~ ~ ~