Periscope Inventors Sir Howard Grubb and Simon Lake

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 Grubbs 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 Grubbs 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 Grubbs factory to make gunsights and periscopes for the war effort and it was during those years that Grubb perfected the periscopes design.