|Place||Europe: Western Front|
|Object type||Optical equipment|
|Physical description||Glass, Leather, Steel, Wood|
|Date made||c 1917|
First World War, 1914-1918
Giant periscope [Das Mastfernrohr] : German Army
German portable telescopic periscope, mounted on a two- wheeled carriage, both painted green. The periscope consists of a steel telescopic mast with upper and lower optical systems attached. The mast is carried in trunnions on the carriage. The periscope has gears to elevate, level and align the optical systems. They also adjust the inclination of the reflector and rotate the mast around its vertical axis.
The telescopic mast is made up of 8 tubes. The bottom tube is connected to the carriage, the other tubes are connected to each other by wire cables and pulleys. The uppermost tube is held in position by catches. When fully erect, the periscope is steadied by three or four guy ropes. One rope connects to the upper side of the lower end of the upper optical system. The other ropes are connected to the uppermost extended section of the mast.
The upper optical system consists of a short rectangular tube which contains a protective window. Behind this is a mirror, placed at an angle. The rectangular tube is attached at right angles to a conical casing, which contains two achromatic lenses. At the bottom of the conical casing is a large lens which has a crosshair on the glass. The lens is pitted near the centre. A strip of leather is attached around the bottom edge of the cone.
The lower optical system is made of a tube casing. At the top of the tube is a lens. There is another near the bottom of the casing. At the bottom of the casing is a prism. At the bottom of the tube is a revolving section with two eyepieces. These give different magnification, depending on the height of the mast. They are marked '3x-8x' and '5x-14x'. The body of periscope is impressed with the 'CARL ZEIS JENA' logo, with 'Nr 228' impressed beneath.
The mast has rungs to allow a person to climb to a metal seat, to push in locking lugs while the mast is being extended. There are two further seats on the carriage, with a handle at each for raising the mast. The two seats originally had padding (missing). At the end of the 'raising spindle' between the two seats, is a logo reading 'CMD' in raised letters.
The cable drum has two handles on either side to extend the periscope up to 25 metres, after the mast has been raised. The cable drum has a measuring bar across it, with the warning label 'Mast nicht uber 25m ausziehen' [Do not extend mast over 25 metres], and markings along the length of the bar, indicating the height of the mast. The cable drum also has markings on it, indicating the height of the mast, as the cables wrap around the drum when it is being extended and retracted. To the left of the cable drum is a small circular handle, impressed with the words 'Auf' and 'Ab' ['On' and 'Off'] with arrows pointing in opposite directions. To the right of the cable drum is a larger circular handle, impressed with the text 'LINKS' and 'RECHTS' ['LEFT' and 'RIGHT']. Below the cable drum is another bar, upon which is a plate reading 'Vor dem Ablegen auf [image of a circle with a vertical line through it] enstellen' with a larger image of a circle with a vertical line through it.
Above the cable drum is a slanted, flat surface upon which observations could be noted on documents or maps. Beneath the cable drum (when periscope is raised) is attached an 'L' shaped rod, to which a small seat, similar to a bicycle seat, was once affixed (now missing). The observer would have sat on this seat when the periscope was in operation.
The two carriage wheels are wooden, with steel rims and hubs. The wheels are painted green; the inside of each wheel is impressed 'Magirus-Ulm 1917'. On each side of the carriage, near the cable drum area, is a stabilising 'spindle plate'.
Called 'Das Mastfernrohr' [the mast telescope] by the Germans, the service history of this First World War giant periscope is unknown. It is believed to be one of only three still in existence and was one of the pieces of military hardware ceded by Germany under the terms of the 1918 Armistice.
This type of periscope was used for the observation of enemy positions, in particular for artillery spotting. It was designed for observation over obstacles between 9 and 25 metres in height, such as hills or buildings. It is portable, being mounted on a carriage, and can be quickly raised or lowered and transported to another location. The periscope was only moved after it had been lowered into a horizontal position and closed.
The upper optical system is conical in shape to allow continued vision from the lower optic system when the mast is swaying slightly. Even with the mast secured by guy ropes, it is unlikely this periscope would have been used in high winds.
The periscope was made by the optical company, Carl Zeiss in Jena, Germany. The carriage was made by the German fire truck company, Magirus Feuerwehrwerke, based in Ulm. The periscope would have been used with a limber, the Beobachtunswagon 02, but it is not present with this periscope.