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trMr. Merrill retired from a long and distinguished career at the New London Division of the Naval Undersea Warfare Center. He currently writes historical works involving that lab and ii accomplishments.


After John P. Holland delivered his practical 53 foot submarine to the U.S. Navy in April 1900, there was an immediate stronger international interest in submarines. By 1914 there were 400 submarines in 16 navies. The first United States periscope patent was granted in 1902, and periscope changes and improvements have been almost continuous since then.

Early submarine success in World War I brought important evidence of the submarine’s capability. Still, acceptability of the submarine as a significant pan of a navy remained in doubt in some circles. Beginning in the 1920s, the United States Navy assumed a broader and aggressive role in submarine design and construction. This led to submarines better matched to naval needs. Preparation for countering the improving submarine was lacking by all sides in the decades between the World Wars.

Operationally the submarine as an asset to the navy improved significantly during this period and prior to World War II. The fleet boat design with a guerre de course mission was in place. Pan of the improvement included the development of a useful periscope capable of helping to protect the submarine and an essential tool for locating its targets.

The submarine accomplished much during World War II; with the nuclear submarine in the decades following World War II, submarine utilization broadened to include submarines designed for attack, deterrence, and intelligence. Multipurpose periscopes beyond optics tailored for the missions provided challenges at that time and now for periscope designers and engineers. During the entire 20m Century, the periscope changed, but was always a key to meeting the mission needs of the submarine.


The concept of seeing around comers with two mirrors, each mounted at the ends of a tube, predated by years the somewhat still primitive but more sophisticated optical submarine periscopes that became a routine part of all submarines by World War I.

Today, it is difficult to imagine a submarine without two periscopes. However, John Holland’s successful HOLLAND VI, the first practical submarine delivered to the United States Navy in April 1900 lacked a periscope. Even though elementary periscopes were extant when the 53 foot HOLLAND VI was under construction, Holland was not inclined to include a periscope in the design.

Holland’s preferred way of sighting was to porpoise the submarine and note the location of the target through 3-inch by 3/4-inch plate-glass viewing ports located around the top of the turret with its 24 inch diameter hatch. 1 His technique of broaching, sighting the target, and then submerging like a porpoise, in lieu of a periscope for visibility and target sighting did not enhance the submarine’s stealth. Several years later, improvements using prisms, lenses and other enhancements brought an improved periscope capability far beyond techniques that had been used such as the camera Lucida2. While improvements have been made, the basic principle (the reflection of objects through mirrors or prisms arranged in a tube) prevailed in the 20111 century. Periscopes were a necessary addition. Without a periscope, even at shallow depths the submarine was running blind underwater.

The evolution of how to build a practical submarine took many years. The advent of the more practical HOLLAND VI in 1900 and the ensuing spurt in submarine construction established the need for submarine operators to know what surrounded them up on the surface but at the same time not to be seen. The optical solution was the only one available. Bringing the optical tube into the pressure hull raised overall submarine design questions as well as optical engineering issues in adapting to the submarine and its environment. The periscope tube penetration of the pressure hull and the attendant potential for water leakage provided persistent engineering demands. During the entire 20th Century, periscope-engineering goals were always present.


By the beginning of the 19111 century, scientists and inventors were using mirrors and prisms to maneuver images for viewing. Yet only towards the end of the century did a submarine application for these techniques come into prominence. The 1880s saw Holland diligently moving his designs towards his ultimate submarine. In 1881, 1883, and 1885, three submarine launching represented Holland’s efforts without periscopes. At the same time, other submarine inventors and builders such as Claude Goubet in France, Thorsten Nordenfeldt in Sweden, and Stefan Drzewiecki in St. Petersburg, Russia were similarly investigating, building and selling submarines with periscope capability.

The March 16, 1916 issue of the Scientific American cast light on the origin of the periscope.

“Who invented the Periscope?

To the editor of the Scientific American:

It is stated by some writers that the periscope, the eye of the submarine, was invented by the French. The first device of this kind to be used in naval warfare was invented by Thomas Doughty in 1864. He was at that time Acting Chief Engineer in the U. S. Navy. During Banks’s Red River expedition Doughty was on the turreted monitor OSAGE. The gunboats were annoyed by bushwhackers and Confederate cavalry picking off their men. Doughty rigged up a sheet iron tube extending from a few feet above the deck to the engine room below, with opening near the top and bottom, and by arrangement of mirrors he could see on shore. When attacked, he would signal the gunners to tum loose, and the enemy soon learned to give OSAGE a wide berth. He little realized that his invention would be utilized in the world’s greatest war … He distinguished himself in the Red River expedition and subsequently was at Mobile. He was one of the old-time, resourceful engineers of the Mississippi River and after the war he resumed his profession. He died in St. Louis in 1896.

W.R. Hodges
St. Louis, Mo ..

A contrary view to U.S. Navy engineer Doughty’s 1864 Civil War periscope appeared in the Professional Notes of the Naval Institute Proceedings in 1914. “The development of the Submarine Boat Periscope-As an historical fact it has been set forth that a submarine boat sight tube was invented in France by Marie Davy,. in 1854. Prisms as a substitute for mirrors in a periscope were reported as early as 1872.

In 1877, during the Russo-Turkish War, Drzewiecki made trials with a submarine using a propeller and equipped with periscope towers. This Polish inventor and scientist is credited with being the first to use an optical tube, the forerunner of the modem periscope. The French 118-foot submarine MORSE included a periscope in 1899.

1900-World War I

Submarine construction flourished and in the United States, the Electric Boat Company laid down the keels for five Holland VI type submarines in the fall of 1900 and two more in 1901. In Great Britain between 1902 and 1905, Vickers Sons and Maxim constructed thirteen Holland-type submarines under Electric Boat Company patent leasing. As the first British submarine (Al), was being built, secrecy was part of the scene. British Navy personnel assigned to the submarine were designated as “for special service. “3 The actual construction was clandestine and took place undercover in a “yacht shed”. The word submarine was avoided because of secrecy. Stealth as a unique attribute of submarines may have been the reason, but submarines and the word secret often go together.

Captain Reginald Bacon RN, the first Inspecting Captain of Submarines and head of the embryonic British Submarine Service, saw the need for a periscope. Because of Captain Bacon’s interest, Sir Howard Grubb, a well-known Irish scientist, authority on optics, and telescope manufacturer, was asked to design a periscope. Grubb’s first United States periscope patent in 1901 was followed with a second United States patent in 1903 with a modification to include the use of relay optics for a wide field of view.

Initially the British Al5 and A3 were fitted with short periscopes. Later, Captain Bacon as a passenger on board a periscope-equipped submarine took over command during an exercise and in the excitement of a pursuit encountered a low bridge with the periscope up. Only the periscope was damaged. Five of the first seven Al British submarines were eventually equipped with the Grubb-designed periscope.

In February 1902, the Royal Navy cabled Isaac Rice (President of Electric Boat) “Course can be accurately kept by Sir Howard Grubb’s periscope.” It has been noted that Frank Cable of Electric Boat, in England at the time, brought back the idea of a periscope to the United States. 6 The United States submarine SSS (MOCCA-SIN) commissioned in 1903 was periscope equipped. Five of the seven initial Electric Boat submarines were equipped with periscopes. For more than fifty years, the periscope was the submarine’s only visual aid. In the late 19S0s, a low light television was installed for under ice operations aboard the nuclear-powered submarine USS SKATE (SSN 578).

The Professional Notes section of the Naval Institute Proceedings for June 1902, disclosed “Recent reports that a new periscope permits a submarine to survey the surface from a depth of SO feet, while formerly to a depth of 20 feet. The new periscope is telescopic.” The rapid increase in the numbers of submarines may be noted in a further comment in the Proceedings stating that the French government ordered the construction of 13 additional submarines.

FULTON, an experimental submarine launched June 12, 1902 by the Electric Boat Company, was eventually sold to Russia. It was intimated that its periscope was useless with the submarine at 20 feet. 7 In the early days, British periscopes were stored on deck in a horizontal position. To operate the periscope, the submarine had to be on the surface; the periscope raised and secured by stays to hold it in position before diving. In the lowered position, the periscope head was sleeved in canvas. Retractable periscope masts appeared later.

Simon Lake, a Connecticut submarine inventor and builder from the Bridgeport area, constructed his first sophisticated submarine, PROTECTOR, in 1902. The 65 foot 130-ton submarine included a Lake periscope patented in 1903 called the omniscope. With its series of lenses and prisms, it allowed the entire horizon to be viewed plus an estimate of the range to a target. Lake was the first to use a rotating periscope on a submarine. An improvement on his periscope was patented the same year and called Combined Ventilating and Observing Tube. (The ventilation concept could be considered a precursor to the German schnorkel8 developed in the 1940s.)

The U. S. Navy tested Lake’s periscope in 1902-03; comparing it with Grubb’s British designs; and it became U.S. Navy’s favored design. 9 Lake offered PROTECTOR to the United States Navy. The Navy hesitated: Russia, then at war with Japan, purchased PROTECTOR from Lake and ordered five more submarines from him. Later, during World War I, Lake built submarines for foreign nations as well as for the United States Navy.

ADDER, the second A class submarine built by Electric Boat Company and commissioned in 1903, conducted a submerged periscope trial. The periscope was rigged through the forward port ventilator. This allowed the submarine to run for three hours at a depth of 11 feet with the conning tower 7-112 feet below the surface of the water.

The advantage of two periscopes soon became apparent: one with larger optics designed for broad area search, with smaller optics in the second periscope optimized for attack. For example, one of the Japanese Holland-type submarines launched in 1905 was equipped with a second periscope. In the 1906, the United States Navy contracted for three submarines, each equipped with two periscopes.

Water leakage and vibration were two long-term periscope-engineering problems. The leakage caused image fogging and improved periscope joints and desiccation techniques provided mitigation. Vibration degraded the performance of the optics. These deficiencies were addressed and relieved as periscopes evolved.

An abundance of names for underwater viewing instruments confronted users through the years. Names for these early periscopes included Hydroscopes, Omniscopes, Storoscopes, Cleptoscopios, Altiscopes, and Eleptoscopes. The names optic tube and periscope persisted. From 1901-1907, as many as thirteen United States patents were awarded for submarine periscopes and their improvement. Two periscope inventors patented 360° or panoramic presentation to the user. Early periscopes, even with targets presented upside down when astern and standing on their ends abeam, still allowed users to judge relative bearings

By the first decade of the 20111 Century, submarines were increased in length and diameter. The tonnage expanded from HOLLAND’s 63 tons to 160 tons with a larger crew; 2 officers and 9 men instead of HOLLAND Vi’s crew of 7. The length increased from 53 to 105 feet. The length made room for a conning tower six feet above the deck, providing an improved position for navigating on the surface. The conning tower also afforded a much better housing for the periscope, now recognized as a vital part of the submarine. In some submarines having the eyepiece of the periscope located in the conning tower instead of the control room, an additional ten feet of periscope height and thus greater observation range was achieved.

It should not be inferred that periscope development or the melding of the periscope with the submarine platform was any-where near a fait accompli at this time. Finding solutions to engineering problems proved difficult as a result of the periscope’s operating in a troublesome salt water environment that included mechanical stresses from movement through the water, changes in temperature, and impact on the periscope and its optical system by water wave action. Water leakage at the seal between the pressure bull and the periscope tube was a constant problem. The wake or feather made by the periscope tube at the water’s surface could give away the submarine’s presence. In 1910, under the aegis of the Anti-submarine Warfare Committee recognizing this weakness sponsored experimental machine gun firings at periscopes as a way to counter enemy submarines.10 Long-term engineering addressed minimizing the periscope’s wake and visibility (optical and later radar).

The long periscope tubes moving through the water vibrated and degraded the images, requiring a reduction in the speed of the submarine. This challenged submarine periscope system designers. Periscope vibration also originated from the submarine itself. It should be noted that during World War II, German U-boats were sometimes limited to speeds of less than five knots when attacking an enemy because of the effect of vibration on optical sighting. 11 For this reason, many attacks were conducted on the surface. The mechanical requirements presented by simply the raising, lowering and positioning of the periscope were enormous and required years for refinement.

Another significant aspect in this evolution relates to the submarine adapting to the operational needs of the periscope. Maintaining the periscope at a nearly constant position with respect to the height of the periscope head above the surface of the water was a formidable task for the evolving submarine. Addressing these requirements became an ongoing quest for both the Navy and those involved in the engineering and manufacture of periscopes and the design of the submarines. Some of the solutions were immediate while others awaited continuing technological advances in the years ahead.

While sighting with the periscope, particularly at low speeds, it was essential to keep the periscope at a fixed height above the water’s surface. Holding the submarine steady within one or two feet made for difficult handling. Torpedoes also prompted submarine handling improvements. The potential for broaching and veering as the torpedo exited the submarine emphasized the need for improved handling. Later, this need for improved handling was addressed when bow planes were added to ease depth keeping and broaching. The United States E-Class submarine launched in 1912 included horizontal bow rudders or bow planes to enhance depth keeping.

Early pre-World War I periscopes typically were fixed height and mounted in a fixed-ahead position. This required the submarine to porpoise to bring the periscope head above the surface. The fixed-ahead required the submarine to change course to look in another direction. Periscopes, which could partially extend and contract into the hull, were an improvement.

Beginning with USS SEAL commissioned in 1912, Simon Lake constructed 28 submarines for the Navy during the period 1910 to 1923. Simon Lake was the only competitor of John Holland and is credited with design aspects of the modem submarine including escape trunk, conning tower, diving planes, control room, and rotating and retractable periscope.

By 1912, simple periscopes and the gyroscopic compass simplified submarine navigation. About this time, retractable cable-controlled periscopes were being introduced in some submarines such as the 0-Class. Optics needed improvement and lenses required frequent desiccation to prevent fogging. The new submarines were designed to keep up with the fleet, and the periscope had to be long enough to see from 30 feet below the surface.

World War I Begins

As mentioned above, at the start of World War I in August 1914, there were 400 submarines in 16 of the world’s navies. Innovations and improvements abounded and effective submarine use as an offensive weapon was slowly beginning to be recognized. By 1914. submarine speed was about 14 knots on the surface and 9 knots submerged. The submarine’s stealth, improving agility, and better Whitehead, Bliss-Leavitt, and other torpedoes plus the periscope contributed to greater acceptance of the submarine as an implement of war. Total acceptance of the submarine was gradual for other reasons. The submarine, not in the capital ship class, was considered as the weapon of the weaker nation; its full potential was not universally grasped.

Acoustic sensing at this time was in a primitive stage of development during World War I; this proved to be a two-edged sword. The submerged submarine’s presence was not as likely to be determined by the searching enemy. Antisubmarine warfare, including weapons such as depth charges to destroy enemy submarines, was in a rudimentary stage. On the other hand, without an acoustic sensing capability, the submarine submerged was deaf and blind when operating below periscope depth. The propellers of nearby surface ships could sometimes be heard in the submarine.

The submarine was handicapped at periscope depth; the distance to the horizon for sighting targets was minimal because of the periscope closeness to the surface of the water. Even surfaced with a raised periscope, the submarine’s range of vision in clear weather was less than the range of vision of an enemy target or submarine hunting surface ship much higher above the surface. A 1915 book on submarines noted that a periscope 20 feet above the water could observe a battleship at 10,000 yards and 2,200 yards at l foot. Submarine-hunting aircraft with their ability quickly to search wide areas of ocean were soon recognized as an additional liability for submarines on both sides.

Longer periscopes allow the submarine to observe at a greater depth but introduced other problems. In addition to increased water pressure, a longer optical tube is more prone to vibration from water action. Increased length causes image dimming due to the greater optical length. The September 2, 1914 issue of the Scientific American reported treating lenses with magnesium fluoride to reduce dimming. Increasing submarine diameter accommodated longer periscopes, increasing height of the upper periscope lens above sea level. This lengthened the distance to the horizon, although not significantly.

Antisubmarine hunting aircraft benefitted greatly due to their height of observation and the distance to the horizon. During World War I, an aircraft at 5000 feet could sweep an area of about 300 miles. This improved; and in World War II, aircraft were responsible for more than half of the 800 U-boat sinkings. The aircraft is assisted further by the wake created by the periscope head as it moves through the surface of the water. Wake reduction was eventually achieved by narrowing the upper portion of the periscope tube to have a pencil-like shape. Periscope heads with dimensions a few inches or less were achieved in some instances. U-boats by 1918 were generally able to look for aircraft in the area before surfacing. In the latter part of World War I, convoys accompanied by aircraft were virtually immune from U-boats.

Dr. Frederick Kollmorgen

Born in Germany in 1871, following university studies, Dr. Kollmorgen directed his career to optical instrumentation and Jens development. Before coming to the United States in 1905 to work at the Keufel and Esser Company in New Jersey, he held positions as an optical advisor with telescope manufacturers in Austria and England. In 1909, he made application for his first submarine periscope patent which was granted October 11, 1911. These basic optical elements and mechanical structural designs pioneered by Kollmorgen continued in use throughout the 2()111 century.

In 1916, when World War I stopped imports of foreign lenses and optical instruments, Kollmorgen headed a small group of scientists and technicians that formed the Kollmorgen Optical Corporation in Brooklyn, New York. Their purpose was to design and build periscopes for the expanding submarine service of the United States Navy. For the remainder of the 2ff’ 20″‘ century, the Kollmorgen name has been associated with numerous state-of-the-art U.S. Navy submarine periscopes and those of other navies.

A recollection by George Carroll Dyer (Vice Admiral, USN, retired) is of interest. In 1919, Dyer was the Commanding Officer of a Holland designed D-class submarine. 13 The Electric Boat Company (EBCO) constructed the three D-class submarines in 1909-1910. D-class improvements cited by EBCO included having two periscopes. Dyer recalls operating with a fixed position periscope:

A recollection by George Carroll Dyer (Vice Admiral, USN, retired) is of interest. In 1919, Dyer was the Commanding Officer of a Holland designed D-class submarine. 13 The Electric Boat Company (EBCO) constructed the three D-class submarines in 1909-1910. D-class improvements cited by EBCO included having two periscopes. Dyer recalls operating with a fixed position periscope: was fixed. It was the last class of submarines that bad the fixed periscope. All the rest bad eyepieces that could be elevated or depressed. If the submarine got a little angled down, you turned the glass up.

Scientific American Supplement No. 2055, May 25, 1915 in “Various Forms of the Periscope” reported on the principles and development of a valuable instrument used in war. The section on submarine periscopes provides a summary of the state of the art at that time.

The general characteristics point out that modern periscopes (1915) have a length of from 16 to 24 feet, and a diameter of 6 to 9 inches, field of view of about 65 degrees and a magnification of 1.25 to 1.5. The optical system can be rotated to face in any required direction and the eyepiece remains fixed.

The article included components of the periscopes built by Sir Howard Grubb, the primary provider for the British Navy:

1. A reversed telescope, giving a reduction of about 0.25
2. A telescope giving a magnification of about 2.0
3. An erecting prism which can be rotated so that the image given by the system is correctly oriented
4. A telescope giving a magnification of 3.0

The two telescopes (1 and 2) were face to face, first reducing the image and then enlarging it. The last telescope ( 4) included a fixed eyepiece and prism, so arranged that the observer looks horizontally at the object. At the focus of the eyepiece are placed a scale and pointer to show the bearing of the object sighted and a ruling to allow the distance to be estimated when the size of the object is known.

Periscope advances included photography. In 1915 between May and December. a British E class submarine (Holland design). using a periscope equipped with a camera in the Sea of Marmara, penetrated Constantinople harbor and took photographs.

Periscope Status 1917

A 1917 book by Marley F. Hay, “Secrets of the Submarine”, summarizes the periscope and some its characteristics at that time. The author credits French submarines with having periscopes 50 years previously (1867). He generalizes that all submarines have two periscopes and some three. Vertical observation of aircraft is the primary use of the third. With diameters of six inches most scopes can be set at 18 or 20 feet above the superstructure deck with the top of the scope 3 or 4 feet above the surface of the water in a moderate sea. The top five or six feet are tapered down to two or three inches in diameter and painted in mottled colors to obscure the periscope. In some instances, a dummy seagull is mounted on top to provide further camouflage. Periscope viewing arranged in the conning tower and in the control room is typical. Other periscope features include horizon scan with a field of vision of 40° -60″, a rotating upper prism to provide images in correct positions, and magnifications of the order of 1-4.

Gyroscope Compass

Elmer Sperry’ s gyroscope compass (patented in 1908) was installed on the submarines E-1 and E-2 commissioned in early 1912. Prior to this invention, only non-ferrous magnetic material could be used for periscope construction. Further, when sub-merged the magnetic compass did not function well in the steel hull as the magnetic compass was surrounded by electromagnetic fields produced by the electric propulsion motors. The compass was mounted outside the hull and viewed with mirrors or a telescope from the conninng tower. In general use of magnetic materials in the vicinity of the compass was minimized where feasible.

Kollmorgen Begins

During the World War I period, Bausch & Lomb, Keuffel and Esser, General Ordnance and the newly founded Kollmorgen Optical Company comprised the sources of U. S. Navy submarine periscopes. The improving submarine platform required periscopes having proper magnification, field of vision, vertical and horizontal movement and other attributes that would optimize the ability of the operator to assess his environment.

Addressing these requirements under a 1916 contract with the Chief of the Department of Construction and Repair, Kollmorgen delivered his two original periscopes (one forward and one aft), to the K-1 (SS-32). The submarine, commissioned in 1914, was 154 feet long, displaced 521 tons, and was one of the twenty U.S. submarines to reach the war zone and report for duty in the Irish Sea and near the Azores. The Navy paid Kollmorgen $1,385 and $1, 685 for the periscopes.

Periscope Disguise

In November 1917, the War Department received a recommendation from a lawyer in Oakland, California, with a suggestion to make the periscope above the water less conspicuous: Disguise the periscope with a decoy of a bird with a glass breast and wings movable by springs. Additional decoys of birds native to the geographical area could provide and make the periscope-mounted decoy a less likely target.

Periscope Assessment

That periscopes were yet to be perfected can be seen in an accounting of periscope problems faced by the fleet of 27 R-Class boats constructed during World War I. Problems included poor focus, lack of eye cushions on the ocular or eyepieces, low power, air bubbles and moisture leaks into the inner tube, Jens scratches, leaks, missing screws, and hydro-dynamically induced vibration at normal submerged speeds.

War Reparations: U-boats

At the end of WWI, six German U-boats were made available to the US Navy at Harwich, England, as part of war reparations. They were brought back to the United States. The Navy’s operational forces carefully examined the U-boats’ capabilities. As a result, the following years were sometimes referred to as the German Years. These German submarines influenced the designs of new United States submarines into the 1930s. The Chief of Naval Operations (CNO) created a list of private contractors and subcontractors who were allowed to examine the technological advances presented by the U-boats. Kollmorgen, by 1920 an important periscope builder, was included in this CNO list of companies allowed to go aboard and examine the German advances in submarine design and construction.

Between the Wars

In the 1920s, the aforementioned Navy examination of German submarines strongly confirmed the potential for improvement in United States submarine design and construction. Additionally with the experience of building more then 70 submarines during the World War I period, the Navy perceived a need to control the contractors. To achieve this, the Navy began an expanded and more direct role concerning submarines and their procurement. The goal of improving the quality of the United States submarine diesel engines, radio communication capability, periscopes, armament, habitability, and other factors led the Navy to take this step. The contractor, not the Navy, drove submarine technology at this time. Acting in the new role of coordinator and catalyst for the first time, Kollmorgen, Sperry Gyroscope Company, Electric Boat Company, and others were supported by the Navy to advance submarine technology.

For the following fifteen years, an ongoing debate regarding the mission of the submarine continued, hampering a consensus regarding the Navy’s submarine needs. The mission choices debated included coastal defense, battle-fleet support, fleet independent operations using stealth to advantage, independent offensive operation, and unrestricted warfare policy. This indecisiveness defining the submarine’s role led to a variety of submarine designs. The mid-l 930s fleet submarine configuration prevailed for the duration of World War II and accommodated the role of unrestricted warfare. This fleet boat design emulated the successful U-boats and warfare of Germany’s World War II course de guerre. German submarine designs such as the U-135, one of the World War I reparation submarines, provided a reliable prototype for submarine design.

These years saw the Navy more actively and broadly participat-ing in the design and engineering of submarines. Moving away from dependence on commercial submarine builders, the Ports-mouth Navy Yard became an important center for submarine engineering development and construction. 17 Between the years 1914-1971, 134 submarines were constructed at Portsmouth. It has been stated that in the pre-nuclear era, more submarines were built at Portsmouth than any other yard. By the mid-1930s, Mare Island Naval Shipyard in California was added to the Navy’s active submarine building program.

In related technical fields, radio communications, underwater sound, and periscopes (Kollmorgen) were given Navy support and encouragement. Advances in these technical areas took place during this period at government, industrial and university locations. 11 With Navy assistance, Kollmorgen’s financial and management practices were improved and their periscopes were widely installed.

German U-boat periscopes were found to be superior to those found on British or American submarines. For example, the periscope heads tapered to less than inch in diameter and provided a reduced and more difficult target at sea level. It was clear that American optics needed upgrading. Improvements followed, but the quality of the 1918 German U-boat periscope still exceeded that of United States periscopes. Quality United States periscopes were available by the late 1930s.

Barr and Stroud Ltd. of Glasgow, Scotland, periscope builders, discussed in their 1922 pamphlet “The Submarine Periscope”, the technical aspects of their state-of-the-art periscopes which consisted of cruising or lookout (surveying the horizon), attack (conning to the target), and night scopes. The article pointed out the light loss in a periscope amounting to as much as 31 percent due to the optics. 19 Sky search capability, desiccating apparatus, pressure capability (of the order of 100 pounds per square inch), a range and inclination finder, and velocity of a target were cited as f earures of importance for submarine periscopes.

The March 1927 issue of the Naval Institute Proceedings cited a Japanese periscope development. Trials aboard the Japanese submarine B-16 included satisfactory testing of a periscope enlarging six diameters, which made it possible to see correctly as high up as 1,000 meters.

Bureau of Construction and Repair (BCR)

Charged with ship construction, including periscopes, Bureau personnel responsible for periscopes were sometimes perceived as reticent in regard to change. A 1983 book on submarines commented on the BCR” … and they fought change every step of the way … That change came at all was through the pushing tactics of the young submarine commanders-who had to live with the product.”

In the post World War I period, the BCR moved toward the standardization of type and design of periscopes. The goal was to improve periscope replacement and parts supply. Previous to 1927, contracts for submarines covered the entire boat, installation and equipment. As a result, there were 70 different periscopes, all similar with the same essential features. This precluded interchangeability and made replacement and parts supply difficult. As a step toward resolving this difficulty, a Manual constructions for Submarine Periscopes was issued. The manual included detailed drawings and specifications from four manufacturers.

U.S. Navy Periscope Builders 1927

Company Periscopes in the Fleet
Bausch & Lomb Optical Co. Periscopes in the Fleet New York, NY 80
Kevin, Bottomly & Baird Glasgow, Scotland 10
Keuffel & Esser Co. New York, NY 50
Kollmorgen Optical Co. Brooklyn, NY 136

United States submarines increased in length and beam beginning in the mid-1920s to 1930s.

Class Length Beam Year
Barracuda 341 feet 27 feet 7 inches 1924
Argonaut 381 feet 33 feet 10 inches 1928
Narwhal 371 feet 33 feet 3 inches 1930
Dolphin 319 feet 27 feet 11 inches 1932
Cachalot 271 feet 24 feet 9 inches 1933
Periscope Length

1916 10-20 feet
1945 30 feet
1960 30-40 feet
1990 46 feet

Typically 40 or 50 feet longer with greater beam than earlier submarines, the new dimensions made it possible to have longer periscopes. The longer periscope tubes required greater rigidity to prevent excessive vibration causing poor images and possible damage to the optics. At that time, existing tubes were constructed of brass, naval bronze, or composites, and low speed was required to reduce vibration. German periscope tubes constructed of steel were found to be more rigid, less susceptible to vibration problems and had experienced little corrosive action due to seawater. Steel became the material of choice for periscope tubes by many of the world’s navies. Periscope bending due to movement through the water was countered by using two tubes: an outer one to resist pressure and an inner to contain the telescopic components.

Periscope Stadimeter

A stadimeter is a device for determining the range to an object of known height. Measuring the angle between the horizon and top of the object (usually the masthead) whose height is generally known provides a basis for the range calculation. The range is independent of the angle of that target to the submarine. By mid-1928, the Navy was evaluating stadimeters. One was a United States Naval Gun Factory type Mark V stadimeter with a range of 8000 yards. The other, made in Jena, Gennany by the Carl Zeiss Company, had a range of 11,000 yards and was of particular interest. Models were placed aboard the three V-Class submarines for evaluation. The 1930s saw periscopes equipped with stadime-ters. In addition to its use in fire control, the stadimeter became useful in both piloting and navigation via the periscope.

Three Periscopes

The mine-laying 381 foot USS ARGONAUT (SS 166), commissioned in 1928 at Portsmouth, was the largest submarine built by the United States until after World War II. It was equipped with three periscopes. Two were raised and lowered by cable hoists, the eyepiece of one in the conning tower and one in the control room. To reduce vibration, the upper periscope was equipped with a streamlined retractable section (fairing). The other scope in the conning tower was raised and lowered hydraulically. Later, it was detennined that this periscope was not needed and it was removed.

Through the years, two persistent periscope problems con-fronted engineers. Previously mentioned, one was vibration of the scope tube as it passed through the water. The other was related to the exposed periscope head and the wake or plume of the above-water portion of the periscope as a target. The fonner was addressed by providing a fairing to streamline the part of the tube exposed to the water. A fairing may reduce vibration at speeds of 6-7 knots or higher. Decreasing Uie target size was addressed by tapering the upper section of the tube and minimizing the size of the head to reduce the observed wake of the above-water portion of the periscope. Camouflaging the exposed section was also implemented.

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