Humanities › History & Culture The History of the Periscope Inventors Sir Howard Grubb and Simon Lake Share Flipboard Email Print RichVintage/Getty Images History & Culture Inventions Famous Inventions Famous Inventors Patents & Trademarks Invention Timelines Computers & The Internet American History African American History African History Ancient History and Culture Asian History European History Genealogy Latin American History Medieval & Renaissance History Military History The 20th Century Women's History View More By Mary Bellis Inventions Expert Mary Bellis covered inventions and inventors for ThoughtCo for 18 years. She is known for her independent films and documentaries, including one about Alexander Graham Bell. our editorial process Mary Bellis Updated March 05, 2019 A periscope is an optical device for conducting observations from a concealed or protected position. Simple periscopes consist of reflecting mirrors and/or prisms at opposite ends of a tube container. The reflecting surfaces are parallel to each other and at a 45° angle to the axis of the tube. The Military This basic 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. Tanks use periscopes extensively: They allow military personnel to check out their situation without leaving the safety of the tank. An important development, the Gundlach rotary periscope, incorporated a rotating top, allowing a tank commander to obtain a 360-degree field of view without moving his seat. This design, patented by Rudolf Gundlach in 1936, first saw use in the Polish 7-TP light tank (produced from 1935 to 1939). Periscopes also enabled soldiers to see over the tops of trenches, thus avoiding exposure to enemy fire (especially from snipers). During World War II, artillery observers and officers used specifically-manufactured periscope binoculars with different mountings. More complex periscopes, using prisms and/or advanced fiber optics instead of mirrors, and providing magnification, operate on submarines and in various fields of science. The overall design of the classical submarine periscope is very simple: two telescopes pointed into each other. If the two telescopes have different individual magnification, the difference between them causes an overall magnification or reduction. Sir Howard Grubb The Navy attributes the invention of the periscope (1902) to Simon Lake and the perfection of the periscope to Sir Howard Grubb. For all its innovations, USS Holland had at least one major flaw; lack of vision when submerged. The submarine had to broach the surface so the crew could look out through windows in the conning tower. Broaching deprived the Holland of one of the submarine’s greatest advantages – stealth. Lack of vision, when submerged, was eventually corrected when Simon Lake used prisms and lenses to develop the omniscope, forerunner of the periscope. Sir Howard Grubb, a designer of astronomical instruments, developed the modern periscope that was first used in Holland-designed British Royal Navy submarines. For more than 50 years, the periscope was the submarine’s only visual aid until underwater television was installed aboard the nuclear-powered submarine USS Nautilus. Thomas Grubb (1800-1878) founded a telescope-making firm in Dublin. Sir Howard Grubb's father was noted for inventing and constructing machinery for printing. In the early 1830s, he made an observatory for his own use equipped with a 9-inch (23cm) telescope. Thomas Grubb's youngest son Howard (1844-1931) joined the firm in 1865, under his hand the company gained a reputation for the first-class Grubb telescopes. During the First World War, demand was on Grubb's factory to make gunsights and periscopes for the war effort and it was during those years that Grubb perfected the periscope's design.