In the 1430s, Johann Gutenberg invented a device to allow those in the back of a crowd to see over other people. The first naval periscope was invented in 1854 by Hippolyte Marie-Davy.Know More
During World War I, some rifles had a periscope attached to allow soldiers to view the area outside the trench. Periscopes are also used in armored vehicles to allow the personnel in the vehicle to remain under cover while viewing the situation in the surrounding area. Rudolph Gundlach patented a rotary periscope for use in tanks in 1936.
The word periscope is derived from the Greek words, peri and scopus, meaning "around" and "to look."