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The History Of The British Submarine Periscope

by Commander David Parry

"I much fear her gallant Commander was only looking at the enemy and didn't care a damn for anything or anybody else I am afraid I might have done the same, so don't wish to throw a stone at him".1

These are the words Admiral Jackie Fisher, First Sea Lord, used to explain the sinking of the submarine A1 on the afternoon of Friday 18th of March 1904 to the then Prince of Wales, later George V. The Commander in question was Lieutenant Loftus Charles Ogilvy Mansergh,2 one of Captain Reginald Bacon's "best of my captains of the boats".3 Mansergh was attacking the cruiser HMS Juno when A1 was rammed and sunk by the Union Castle liner, Berwick Castle off the Nab Tower south of Portsmouth. This was the first fatal accident for the Royal Navy's embryonic Submarine Service.

Like the many hundreds of submarine COs that would follow him, Mansergh would have been working his periscope hard in search of the attack solution to fire his torpedo at the Juno. But periscopes, rather like the submarines in which they were fitted, where in their infancy.4

Who invented the first submarine periscope, or indeed the periscope, is contentious and irrelevant to this history of British submarine periscopes. Suffice to say here that the first operational use of a periscope, invented by Thomas Doughty in 1864, was in the turreted monitor Osage during the American Civil War5; that the French submarine Morse had a periscope in 18996; and that in the late 19th century in the United States, Simon Lake was busy with an omniscope (a fixed tube) for the submarines he was developing in parallel with John Holland.7 But, in the case of British submarines, it was Captain Reginald Bacon, the first Inspecting Captain of Submarines (ICS) who claims the accolade.

Bacon was a Fisher appointee who had acclaimed him as "acknowledged to be the cleverest officer in the Navy"8 (he achieved a first-class certificate for every exam he took).9 On being promoted Captain in June 1900 he was appointed ICS.10 Almost his first task was to find a resolution for what he saw as the greatest difficulty to be experienced by submarines: their blindness when dived. With no periscopes submarines had to broach so the crew could peer through a small three-inch plate glass viewing port11 to see where they were.12

Bacon used his intellect to solve the problem. Following trials on the Vernon of a tube fitted with prisms at top and bottom Bacon realised he had a solution. Improvements led to the creation of a rudimentary periscope, or rather like Lake, an omniscope, which had a ball and socket at its foot so that it could be lowered and was held up by stays when upright when the eyepiece were shipped.13 It was fitted to the first two Holland boats. Although Bacon and his successor Edgar Lees continued to dabble in periscope development the real evolution came from the Dublin-based optical designer Sir Howard Grubb who took Bacon's ideas and was very quickly able to produce and patent in 1901 the forerunner of all future optical periscopes.14 Bacon boasted of this triumph by cabling the President of Electric Boat, Isaac Rice in February 1902 to tell him that "Course can be accurately kept by Sir Howard Grubb's periscope"15 Captain Cable USN, the Electric Boat Company representative at Vickers took the design back to the United States.16

The Howard Grubb periscopes in the A Class and B Class that followed the first Hollands were in the conning tower (It would have been one of these Grubb instruments through which Mansergh was stalking his quarry). After the loss of the A1 a lower conning tower hatch was added and when on the surface the periscope was lowered through this to the deck over the battery. It was assumed that when dived, the periscope would always be raised and the captain would use it in the conning tower. They were raised on either a wire or chain with a small motor for training.

The C1-C16 of the first batch of the C Class were the first submarines to have two periscopes: "The C boats are fitted with two periscopes instead of one. The reason for this is because the range of vision of this instrument is barely 60 degrees, and thus […] It is impossible for the officer in command of the submarine to keep constantly in view a certain portion of the surface when the vessel is submerged. The two periscopes obviate this difficulty".17

Both periscopes where hand raised,18 'one for the Captain and the other for the look-out man continuously sweeping the horizon'19 - the 'All Round Look' was born? - although they were both the same type of periscope. One a fitted through the conning tower as in the previous classes, the other just aft of the conning tower and both had standards. But the follow-on submarines, C21-C38,20 reverted to one stereoscopic periscope which again appears to go through the conning tower21 although at 21 feet it was much longer than the periscopes in the earlier C Class boats whose periscopes were only 12-13 feet long. Consequently, a space for housing the periscope was created in the battery tank and the periscope well was conceived.22 The D Class again had two periscopes neither of which went through the conning tower and they had standards that were six feet above the bridge deck. The forward periscope had to be off the centreline by six inches to accommodate the drop keel release gear and some were raised by hand others by a small electric motor.23

Although these periscopes continued to have problems with strength, vibration, water tightness and desiccation, they were fitted to all classes of submarine until 1915. However, in 1911 a delegation visited Officino Galileo in Florence, Goertz in Berlin and Lacour-Bethiot in Paris to see and compare their periscopes with those of Howard Grubb. The Howard Grubb periscopes were found wanting for all the others were optically and mechanically better. Twelve of the Geortz periscopes were ordered by the Admiralty but it is not known what happened to them, they do not seem to have be fitted in British submarines. The French Lacour-Bethiot was trialled in the C34 and proved very satisfactory. But again, there appears to have been no follow-up action. However, Messrs Kelvin, Bottomley and Baird24 acquired the rights to manufacture both the Italian and German periscopes. Kelvin supplied periscopes to complement the Howard Grubb periscope in both the K Class and L Class although whether these were Italian, German or a Kelvin-developed periscope is not known.25 But it is known that Kelvin did not dislodge Howard Grubb who clearly took the message to heart for the periscopes for the E Class where much improved. Those in E1-E6 were made of brass and the periscopes in the later boats of non-magnetic steel tubes.

Based on the experience in WW1, the choice of periscopes in the inter-war classes of submarine was a compromise between the height of the periscope standards and the submarine's silhouette, keel to periscope-top height for shallow water, submarine control when dived, surface to fin-top depth for safety, and the ability to penetrate submarine nets. In at least the case of the Swordfish Class in 1931, Rear Admiral Charles Little, Rear Admiral (S) and a renowned WW1 submariner, won the safety case reflecting, perhaps, the emphasis of submarine operations at the time. But there were some innovations and anomalies. Periscope standards became tied to each other for strength and from the J Class and K Class onwards periscope raising was hydraulic. Both the X1 and the L Class had three periscopes. In the case of the L Class the third, Kelvin periscope, had no standard of its own but was supported by the tie between the two periscope standards. The M Class also had three periscopes: one was used for range finding and the extra periscope, fitted to the director tower just aft of the 12-inch gun, was used for gun control.26

One problem that persisted was that of desiccation. Both Howard Grubb and Kelvin provided desiccating pumps which dried the air inside the periscope. But the process took anything up to 24-hours. Then Lieutenant Commander F L Newhouse came up with the idea of creating a vacuum inside the periscope, a process that only took 10 minutes. In 1920 he applied to the Royal Commission on Awards to Inventors but, even though his invention was successful, alas, he failed in his petition.27 Barr and Stroud used the Newhouse desiccator.28

It was with the Howard Grubb periscopes that all of the most well-known submarine COs of WW1 learned and practised their trade: Laurence, Horton, Nasmith, Cromie, Holbrook, Boyle et al. Not that it was an exact science by any stroke of imagination. Navigation had to be achieved by taking relative bearings through a periscope related to a magnetic compass whose deviation varied with the state of machinery. This led to the expression "By Guess and By God".29 Attacking too, was an inexact science and had to be achieved solely by the CO's 'periscope eye'. To achieve an attack solution the CO had to determine the target's course, range and speed so that a deflection angle (DA), or aim off, could be estimated. Course was assessed by the target's bearing and angle on the bow; various indicators, such as type of target, bow wave and stern wave would suggest the target's speed (asdic was in its infancy so no revolution count); but range was possibly more deceiving when looking at a target from only a few feet above the water exacerbated by factors like visibility and target size.

The first intimation for Barr and Stroud that they would have such a long and illustrious association with submarine periscopes came in 1903 when the company was approached by the Holland Torpedo Boat Company to design a rangefinder for submarine periscopes. The company was a natural choice for it was making most of the Navy's rangefinders and had a close working relationship with the Admiralty. Some prescient work was done with a conclusion being drawn that the best way to solve the problem was to incorporate a vertical rangefinder in the upper part of the periscope tube itself. However, there was no apparent enthusiasm from the Admiralty so any ideas were not taken to a design stage.

In December 1915 Commodore Sydney Hall, the now Inspecting Captain of Submarines,30 met Barr and Stroud's Chief Scientific Assistant, James French, to resurrect the earlier rangefinder work. A mock-up was made and shown to Hall in July 1916 and shortly afterwards the company received orders for 13 FY1 periscopes.31 The first periscope was handed over within a year of being ordered to be fitted in the minelayer submarine M3 in 1919.32 The rangefinder was on the principles of a stadimeter33 and this became the standard way of range finding for British periscopes. American Kollmorgen periscopes used the same principle34 but the German Zeiss periscopes relied on a graticule.35.

At the same time Howard Grubb had moved his manufacturing premises from Dublin to St Albans because the periscopes were thought to be at threat crossing the Irish Sea and the Admiralty was uncertain about the Irish political situation.36 It was a move conducted in great secrecy and probably under the Defence of the Realm Act37 with the acquisition of a factory belonging to Smith's Printing Agency not being publicly disclosed as should have been the norm. It is doubtful, however, that anything more than refurbishment work on legacy periscopes was done in St Albans for, by 1925, Barr and Stroud had established themselves as the pre-eminent, indeed, what would become, the monopoly supplier of submarine periscopes.38 One of the principal reasons for this was that Howard Grubb supplied their periscopes to the shipbuilder Vickers whereas Barr and Stroud were able to develop a direct relationship with the Admiralty.39 Howard Grubb reverted to telescope production.

The years following the FY1 saw improvements being made and the periscope's more familiar form beginning to take shape. A bifocal, sky searching periscope known as CH240 was developed in 1917 with an internal focusing lens so the user did not have to remove his eye from the eyepiece to change focus as he had to do on the earlier periscopes. It also had rotating grips on the handles to change magnification and a new range estimator was introduced. This had the added advantage of being able to range in the horizontal plane as well as the vertical plane so if the target's length was known, the angle on the bow could be determined from the virtual length and thereby the targets course.41 This capability disappeared from later periscopes.

Barr and Stroud supplied seven periscopes to the Royal Navy in 1921: four CH3 unifocals, and three CH4 with periscope sky search capability. A further CH7, an improved CH4 with a rangefinder added was provided in 1923.42 Soon afterwards, complaints of eyestrain by submarine watch-keepers having to spend long hours on a monocular periscope led to the development of a binocular periscope in 1924. This was the CK1 periscope that went into service in 192543 but the Admiralty made sure that the technique of producing the binocular vision in an instrument that was just 60% greater at the top than the monocular version was kept a secret. Indeed, the patent was not taken out until the 1950s.44 It was also in the mid-1920s that the Admiralty Research Laboratory started looking at the prospect of taking photographs through periscopes. At that time the desiderata were to take a photograph following an attack while limiting the time the periscope was unavailable to the command. Barr and Stroud took over the work in 1927 and trials were conducted on the submarine L22 . By the time Barr and Stroud presented their proposal in 1933 the operational requirement had changed to a new employment of the submarine, namely reconnaissance.45 In 1942 special Kodak periscope cameras were being introduced46 but it was not until 1958 with the introduction of the CK25 search periscope (a modification of the Oberon's class CK24) that a periscope had a proper inbuilt 'photographic'capability.47 Once fitted, however, submarines had an excellent intelligence-gathering enhancement for both photographic reconnaissance and the underwater-look capability,48 both of which were taught and exercised during Perisher and used extensively by operational submarines.

When the submarine fleet began to be modernised in the late 1920s, with a special focus on the long-range operations demanded by the Far East theatre of operations, new periscopes were developed for the new O Class submarines: the CK2 binocular search periscope with sky search capability and the CH21 bifocal attack periscope resulted. CK8 and CK9 binocular search periscopes and CH51 and CH55 bifocal attack periscopes were fitted in the new T CLass and U CLass submarines in the late 1930s. The principal differences were the length of the periscope depending on the class of submarine.49 By this time Barr and Stroud had provided 150 periscopes to the Royal Navy50 and a Naval central depot for periscope repair was set up at Fort Blockhouse, Gosport . (The Admiralty, ever economically minded, had the periscopes shipped to Gosport by sea rather than rail which was considered too expensive.)51

But none of this, or what followed, may have happened for in 1929 the Admiralty's single source of periscope supply was under threat. Barr and Stroud had survived the immediate post-war period with its cancellation of orders and subsequent lack of new orders but, by 1929, business was looking bleak. Key to survival was a contract for Fire Control Directors and Tables which the company had already developed, at a loss, under a secret agreement with the Admiralty. The Board wrote to the Director of Navy Contracts with a letter that laid bare the facts and the strategic importance of the company. Without mentioning it directly, the letter also referred to the close symbiotic relationship that the company and the Admiralty had enjoyed since 1892 and the earliest days of rangefinders.52 The letter fell on fertile ground, the company got its orders and, to the good fortune of the future Submarine Service, survived.53.

It was the latter group of periscopes that were the standard fit in British submarines throughout WW2 although some important improvements were made along the way. The most important was a method to reduce the loss of light in the periscope column. The periscopes usually contained over 20 air-glass surfaces each suffering transmission loss of around 5%. By 1940 Barr and Stroud had perfected a technique to coat the surfaces to increase the light transmission by about 60% and thus greatly improve both day and night-time visibility. In 1941 the Admiralty ordered that all submarine periscopes be 'bloomed' with this coating.54 Another development was an air blast technique to clear the window of the search periscopes when they were blinded by sea spray. And, while the subject of window cleaning was on the agenda, the Admiralty Research Laboratory in 1944, perhaps belatedly, gave some advice on how best to clean periscopes. The glass was to be wiped using a clean linen cloth and a fluid such as, in order of priority, pure alcohol, ether or methylated spirits.55 (Wardroom gin and vodka were later found to be suitable substitutes for substances not normally carried in submarines). In 1943 a 40-foot bifocal night search periscope was developed. This periscope, the CK14, was to go in the A Class submarines along with the CH66 and then, later, the CH73 attack periscopes.

Development of a combined radar and optical periscope was started by Barr and Stroud in 1945 at the invitation of the Admiralty Signals Establishment. Following successful trials in HMS Fleetwood56/57 a radar pulse burst capability was developed and the first prototype was ready by 1950. After a further two iterations a working periscope for the T Class conversions was ready by 1954 in a CK17, bifocal, binocular night periscope with the JT1 periscope radar.58 However, despite being fitted in the T Class conversions , the Porpoise Class and even the Dreadnought , (later removed), and despite being used operationally successfully at least once, it was not popular with COs for its clear submarine characteristics were too easily detected and it required too much mast exposure especially during an attack.59

It was while this work on a periscope radar ranging was progressing that a radio main mast assembly was developed. This was a high-frequency and very high-frequency aerial, known as the ALN and AP 67004 or Conical Log Spiral (CLS) respectively. The mast was capable of transmitting 500 watts and it too, initially went into the T Class conversions , and then the Porpoise Class new build.60 Thereafter all submarines had an ALN or its successor fitted. The T Class conversions with their streamlining brought new problems for the periscopes in the form of vibration due to the higher speeds. These problems were resolved by replacing the bronze of the periscope tube with austenitic (stainless) steel and by dividing the periscope into two parts with a focal plane between the two sections which were joined by precision 'O' rings improving watertightness.61

Royal Navy submarines were now beginning to conduct longer patrols but in a hostile radar environment.

While the snorkel gave much protection from being detected by radar by virtue of the submarine not having to surface to charge its batteries, in the days before satellites submarines still needed to fix their positions by astronomical navigation. This meant conducting an 'action-surface'62 at either morning or evening twilight for a star fix or in broad daylight for an altitude of the sun. This was clearly unacceptable and a means of taking sights using the periscope was required. Indeed, so extensive were the new demands being made on the use of the periscopes that an "epoch-making"meeting was held in Bath in May 1955 with the object of seeing how all the new requirements could be incorporated into the binocular and monocular periscopes while they retained their ability to provide the optical capability. The meeting was attended by representatives of FOSM, the Naval Equipment, Construction, Electrical and Ordnance Department, Admiralty Compass, Gunnery and Signals and Radar Establishments as well as Barr and Stroud.

As a consequence, the scene was set for the modern periscope beginning with Barr and Stroud working in collaboration with the Admiralty Compass Observatory to provide a periscope sextant capability. Within six months a prototype was installed in HMS Taciturn in 1955. At the same time, the University of Cambridge was experimenting with periscope sun sights in HMS Seraph using a rather complicated set up to take photographs of the sun from which an altitude could be derived. The conclusions, however, were not conclusively favourable, (nor is there any comment by the CO about having his periscope taken over for lengthy periods),63 so how much of this work found its way back into the Barr and Stroud design is not known. The new design had a mechanism so that the sextant sighting prism's elevation could be known accurately. This was above an artificial horizon situated at the bottom of the periscope, as close as possible to the meta-centre of the submarine where acceleration forces were the least and an elegant way of compensating for the error caused by the flex in the optical train down periscope tube was developed. The results showed that sights were as accurate as from a handheld sextant for sun lines but it took another two years development work before the periscope was good enough for star sights.64 The sextant capability came to be known as the Artificial Horizon Periscope Sextant (AHPS) and was first fitted in the CH67 for the T Class conversions. Paired up with the CK17, some 35 sets of these periscopes were fitted.65.

The CH67 was to morph into the longer CH70 range of periscopes: CH73 for the A Class ; CH74 for the Porpoise Class and then the Oberon Class from 1962; CH75 for HMS Dreadnought and theValiant Class; CH78 with radar and image intensifier (II)66 for the Resolution Class; and CH79 for the Swiftsure class. Although there is a suspicion that the practice started earlier,67 from 1959 or thereabouts, when Teacher was embarked in a Perisher boat the search periscope was removed and a special CH76 periscope fitted. Accompanying the development of the CH70 range of periscopes was an adventure into laser-ranging with the CH80. But the submariners' visceral antipathy towards transmissions of any sort from a submarine rejected the project.68

With the prototype sextant capability in HMS Taciturn came another innovation designed by the Navy's Barr and Stroud liaison officer, Commander Lane. This was an electrically powered roundabout that allowed the observer to remain seated and control the turning motion of the periscope by foot pedals thus resolving both the torque issues and watch keeper tiredness and thereby improving alertness. It became known as the 'Lane Roundabout'.69 Subsequent generations of submarine periscope watch-keepers have unconsciously thanked Commander Lane for this innovation.

There was another ramification of the hostile radar environment. That was how to reduce the radar signature of the periscopes and principally the snort head. The Germans had experimented in camouflaging their U-boat conning towers and later, schnorkels, with radar absorbent material.70 In 1945 the Admiralty started looking at the same issue for periscopes and the snort head in a similar material using Buna Neoprene rubber from Germany.71 Matters had not improved by 1954 when Captain J E Slaughter, Captain S/M One, wrote a letter suggesting urgent resolution to the problem of radar detection. He quoted an exercise where a snorting submarine was detected at a range of 54 miles by an aircraft, ranges of 40 miles detection being apparently quite common.72 In 1962 the issue had still not been resolved and eyes were now turned towards the Dutch, comparing their pear-shaped snort with the British snort mast coated in a Plessey Radar Absorbent Material (RAM) which protected against both X and S bands and had been shown to reduce radar signature by 40%. The conclusion was a recommendation that a Staff Requirement be raised for RAM coating.73

Although RAM began to be fitted, the real culprit for radar detection was the water flume or feather, especially in calm seas. The visibility of the feather had of course been a problem since the first days of submarine periscopes and along the way a number of ventures had been made in how to reduce it. One innovative suggestion came in 1941 from an Austrian internee on the Isle of Man, Victor Stohanzel. Stohanzel was a prolific inventor well-known to the Admiralty. His idea on this occasion was to put a fairing around the periscope but it was rejected.74 Perhaps he was both imaginative and prescient for both US and RN submarines today have something working on a similar principle.

The 1970s saw the start of more advanced technologies playing their part in the development of masts and periscopes. The first was the development of an Electronic Support Measures (ESM) mast. This was developed by Barr and Stroud in collaboration with Decca Ltd. which resulted in the AYG/AYH ESM masts fitted to the Oberon and the Resolution classes. There then followed the development of thermal imaging techniques into submarine periscopes75 and, in 1977, the first fully operational infra-red submarine periscope, the CH82 (a modified CH74) was completed. The start of the introduction of these new sorts of technologies meant that special ways of accommodating the waveguides and coaxial cables that carry the signals down the periscopes to the Control Room had to be devised. Rotating joints and slip rings were the answer.76

The Valiant Class were fitted with the CH75 attack periscope, similar to the Oberon's CH74, and the CK25 search periscope with its photographic capability. Out went the 'Lane Roundabout' and in came torque assist. The Swiftsure Class were fitted with the CH79 attack periscope which again differed little from the CH74 and CH75 periscopes. The Swiftsure search periscope was the CK29, again with the now standard photographic capability.77 The latter was replaced by the CK33 in the 1980s which was a CK29 modified with a radar warning and direction finding (DF) antenna package provided by Racal-Decca under the EW/ESM Morthoe project.78 The CH79 was replaced by the CH83, a quasi-binocular attack periscope with thermal imaging (TI), electronic control, a stub of a VHF/UHF communications aerial called AVS and a TV camera. The TV was a quantum change in submarine command practice for the surface picture was no longer the sole province of the captain but could be shared with the command team.

The Upholder Class's, although only in commission for a short time, should not be forgotten for their periscopes the CH85 and CK35 introduced the remote control of key functions such as elevation and depression of line of sight, image magnification, low-light TV, range measurement and periscope rotation. Control and imagery from all the periscope sensors, infra-red (IR), II and TV, could now be displayed in the control room for the benefit of the whole command team.79 Then came the Trafalgar Class's submarines.

To complement their new sonar and command system outfits the Trafalgar Class were provided with the last and most sophisticated hull-penetrating periscopes. The attack periscope was a CH84 similar to the CH83 in the Swiftsure submarines with II and TV and with TI as standard. (Some special fit submarines had previously had this capability). But the search periscope was a highly sophisticated CK34 binocular periscope with the latest electronic AHPS IV, the Morthoe EW/ESM and AVS.80 A welcome addition was all the controls and read-out been contained in two simplified panels on either side of the ocular box.81 To overcome vibration issues both these periscopes had a wider diameter tube made of a higher grade of stainless steel with special anti-vibration optics.82

With the advent of the Astute Class's, Barr and Stroud was part of the Thales Group having been part of Pilkington Group since 1977. It was just before the company was taken over by Thales that its first optronic mast, CM10, was trialled in HMS Trenchant in 1998.83 This put the company in a good position to win the competitive tender against Sagem of France and Kollmorgen of the USA84 for the Astute programme. While the CM10 was sold to the Japanese Defence Force, thus re-establishing a link with Japan from the 1930s, Thales improved on their prototype to create the Low-Profile Variant Optronic Mast that is now at sea with the Astute Class's submarines with each boat having two masts. These masts can confidently be called multi-purpose for they have IR, TV and II all of which are 3-axis stabilised and in a more compact package than the CM10. These masts have no need for an optical tube. Rather, the TI, II and TV are passed to screens in the control room by wire while the mast itself is contained within the fin of the submarine. The knock-on effect is twofold: the fin can be positioned in the optimum position for hydrodynamics; and the control room becomes more of a command centre imposing different constraints and certainly greater opportunities for how the commanding officer commands his submarine. But the iconic, sibilantic hiss of a periscope being raised or lowered has disappeared from the submarine control room for good.

For a century the sine qua non for a submarine commanding officer has been that of a good 'periscope eye'. It is what the command course, be it the Periscope Course, the Commanding Officers Qualifying Course or the Submarine Command Course hoped or hopes to expose, develop and exploit. But as there are so many aspects to 'periscope eye', they make it almost indefinable. Captain George Simpson, in his autobiography, Periscope View, reflects on his time on Perisher, "This sense of relative position in the Captain's mind's eye is what the success and the safety of the submarine chiefly depend upon".85 A few generations later, Admiral Sandy Woodward reflected on the same issue when referring to holding a mental picture of the surface scene, "imagine sticking your head out of a manhole in Piccadilly Circus, taking one quick swivelling look around, ducking back down into the sewer and then trying to remember all that you have seen. The idea is to generate sufficiently accurate recall and timing to avoid a double-decker bus running over your head next time you pop up through the manhole".86 Simpson again, talking about one of his commanding officers when he was Captain 10th Flotilla, Lieutenant Edward A Woodward (no known relation) says "He had a particularly good eye for periscope attack".87 These are two aspects of 'periscope eye': the all-round surface picture and the attack. Commodore Martin McPherson struggles with the debate in his paper 'Perisher: The Making of a Submarine Commander' and adds another dimension "not get[ing] lost in the box".88 But he comes to an indistinct conclusion.89

What is clear, however, is that the greatest instrument for a commanding officer's success and safety over the past century has been his periscope. Until the rampage of technology that came with the digital revolution the development of the periscope had been evolutionary rather than revolutionary. While the submarine commanding officer may have honed his skills in the use of his periscopes over those years, their usage remained principally the same and the idiosyncratic rituals have been passed by Perisher Teacher to Perisher student across the generations.

Then came the passing of the electronic and diesel batons to the digital and nuclear age. The submarine commanding officer had to learn, accommodate and employ a plethora of new systems and sensors; a new way of fighting the submarine evolved as the Cold War developed. Not least in enforcing these changes has been the modern periscope with its inbuilt range of sensors and associated control room controls and displays. Today the submarine commanding officer no longer uses his eye at the periscope. But if the traditions of the Submarine Service endure that does not mean to say that the qualities that coalesce into the attribute of 'periscope eye' will in any way be diminished


  1. Compton-Hall, Richard, Submarine Boats: The beginnings of underwater warfare, London, Conway, 1983, p.22 Compton Hall is quoting Fisher's letter to the Prince of Wales dated 20 March 1904
  2. Evans, AS, Beneath the Waves, London, William Kimber, 1986, p.17
  3. Bacon, Admiral Sir Reginald, From 1900 Onward,, London, Hutchinson, 1940, p.75
  4. Merrill, John, Looking around: a short history of submarine periscopes, Southngton, CT, Strong Books, 2002,
    Note 5 avers that A1's periscope was non-rotatable and that may have contributed to the accident. His assertion, however, is not qualified and even Bacon, in his earliest periscope experiments, realised the requirement for rotation.
  5. Scientific American, Who invented the Periscope?, 16 March 1916
  6. The Spectator, The recent trials of the new French submarine boat 'Morse', 12 January 1901, p.2
  7. Compton-Hall, op. cit., p.118
  8. Mackay, Roddock F, Fisher of Kilverstone, Oxford Clarendon Press 1993, p.297
  9. ADM 186/42 Bacon's Service Record
  10. ADM 196/42 Bacon was actually appointed to HMS President for special services. This meant he was on the staff of Rear Admiral Arthur Wilson, Controller of the Navy. The 'special services' was because submarines were still be secret
  11. Merrill, John, Looking around: a short history of submarine periscopes, Southngton, CT, Strong Books, 2002,p. 9
  12. Bacon, op. cit., p.54
  13. BR 3053, Chapter 22, 22.3 Periscopes
  14. Merrill op. cit. p.15, Grubb's first application for a United States'patent for an "Apparatus for facilitating the siting of distant objects from submarine boats, barbettes etc." was filed in December 1901.
  15. Merrill op. cit. p. 16
  16. Bacon op. cit. Bacon says that Cable was with the Holland Boat Company and implies that he took Bacon's ideas for periscope back to the United States which is probably true for Cable left after working-up the first Holland boat during which he had used Bacon's periscope. However, by June 1900 John Holland had sold out to the Electric Boat Company as he clearly states in a letter to CE Foss, Chairman of the Committee on Naval Affairs, so Cable would have been a representative of that company. (Poluhowich, John, The Argonaut: Submarine Legacy of Simon Lake, College Station, Texas A&M University Press, 1999, p. 90
  17. Domville-Fife and Hopkins, Charles William and Ommaney, Submarines of The World's Navies, London, Frances Griffiths, 1911, p.23
  18. The full batch was C1-C18 but C17 and C18 were built in Chatham rather than at Vickers and the records do not survive although it is most likely they had the same fit as the other boats of the batch.
  19. RNSM BR 3043, Chapter 22, 22.3 Periscopes
  20. Again, C19 and C20 were built in Chatham and not Vickers.
  21. Akermann,Paul, Encyclopaedia of British Submarines 1901-1955, Penzance, Maritime Books, 1989, p.130
  22. RNSM BR 3053, Chapter 22, 22.3 Periscopes
  23. RNSM BR 3053, Chapter 22, 22.3 Periscopes
  24. Now Kelvin Hughes
  25. RNSM BR 3053, Chapter 22, 22.3 Periscopes
  26. BR 3053, Chapter 22, 22.3 Periscopes
  27. TNA T173/725 Claim of Lieutenant Commander FL Newhouse in respect of desiccators for submarine periscopes
  28. GUA UGD 295/26/1/69 Barr and Stroud had problems installing the CH21 periscope into HMS Oberon and used the Newhouse desiccator extensively.
  29. Carr, William Guy, By Guess and By God, London, Hutchinson, 1930, An Introductory Note
  30. Hall had been ICS previously 1906-1910 (ADM 196/43) but had been sacked by Admiral Arthur Wilson, First Sea Lord with whom he disagreed. Churchill said Hall was "A d—d sight too pertinacious"(Churchill, Winston S, Companion Volume II Part 2, London, Heineman, 1969, p. 1365
  31. The nomenclature of periscopes derives from Barr and Stroud's register book. The FY name derives from its predecessor army rangefinders (the periscope rangefinder was essentially an army rangefinder turned through 90°). The army rangefinders were all designated with the first letter 'F'. Later naval products adopted first letter 'C'. The attack periscope came after naval gunnery range finders by which time they went under the designator 'CH'. The search periscopes came later, hence 'CK'.
  32. Moss and Russell op. cit. p. 83 One of the FY1 periscopes was sent to the USA and others were sold to the French Navy and then, later and FY2 was sold to the Polish Navy
  33. A stadimeter uses an image of a target and a known height on the target to determine an angle from which range can be determined.
  34. 34 accessed January 2018
  35. accessed January 2018
  36. Sisson, George M, Mirror Images in Vistas of Astronomy, 1992, Volume 35. pp.345-397
  37. The Defence of the Realm Act allowed the government to seize factories.
  38. Sisson, op. cit. and Email correspondence with Mike Neighbour, St Albans Own East End January 2018
  39. Sambrook, Stephen C, The Optical Munitions Industry in Great Britain 1888-1923, London, Pickering and Chatto, 2013, p. 185
  40. CH1 was and FY1 periscope without the rangefinder
  41. Moss and Russell op. cit. p. 113
  42. Moss and Russell op. cit. p.113 and Thales: 100 years of submarine visual system innovation, a booklet printed in 2017 to celebrate 100 years of the company supplying periscopes to the Royal Navy.
  43. Moss and Russell op. cit. p. 113
  44. The patent was not published until 1950
  45. TNA ADM 212/90 Photography through a submarine Periscope
  46. TNA ADM 116/4586 Submarine General Memorandum number 78 dated 30 October 1942
  47. Thales: 100 years of submarine visual system innovation, a booklet printed in 2017 to celebrate 100 years of the company supplying periscopes to the Royal Navy.
  48. Taking photographs of shorelines, for example, and hull-fittings of ships as the submarine went underneath them.
  49. Moss and Russell op. cit. p. 121
  50. Moss and Russell op. cit. p. 121 A further 85 periscopes have been sold to the USA, USSR, Polish, Yugoslavian and Swedish navies to which were added, later, the Portuguese, Danish, Hellenic, Estonian, and free French navies. In 1923 Barr and Stroud were allowed to start providing the French with periscopes but 'Chinese walls' were imposed on them by the Admiralty (TNA ADM 1/8635/17 Submarine periscopes for the French Navy ). Manufacture then moved under licence to France and by 1939, the French Navy had 80 Barr and Stroud periscopes. (Moss and Russell, op. cit. P.121). And by 1931 all Japanese submarines were fitted with Barr and Stroud periscopes which they no doubt used in WW2. (Moss Russell op. cit. p.121 Note 72 relates a report in the Daily Telegraph 12 October 1931 claiming that all Japanese submarines were equipped with Barr and Stroud periscopes.)
  51. AFL 186/1933 Submarine Periscopes Reports available at
  52. Sambrook, op. cit. p. 191
  53. GUA UGD 295/26/1/24 Letter from Barr and Stroud to the Director of Navy Contracts dated 8 February 1929
  54. Moss and Russell op. cit. P.148
  55. TNA ADM 204/648 Cleaning of optical glass surfaces
  56. ADM 220/1080 Trials of experimental submarine periscope radar ranging system in HMS Fleetwood
  57. GUA UGD 295/26/1/87 Dr. Strang's notes on history of Barr & Stroud Ltd Handwritten notes by Dr. Strang relate to similar but different trials. According to Dr. Strang's record the Admiralty conducted trials at Eastney against a specification requiring the radar to have a satisfactory echo at 8,000yds. In fact, ranges greater than this were achieved with the target frigate being asked to go further and further away until she complained she was in danger of running aground on the coast of France!
  58. Moss and Russell, op. cit., pp. 154-156 and Thales: 100 years of submarine visual system innovation, a booklet printed in 2017 to celebrate 100 years of the company supplying periscopes to the Royal Navy.
  59. Dits and Bits: Periscope Radar Ranging. The successful use was from HMS Tiptoe during operation Quiet Sentinel in 1969 when she ranged on a Russian ship.
  60. Moss and Russell, op. cit. p. 156 and HMS Collingwood Heritage Collection at
  61. Moss and Russell, op. cit. p. 164
  62. Surfacing at Action Stations and staying on the surface just long enough for navigator to take his sights.
  63. TNA ADM 1/25365 Further notes on sub sights through a periscope
  64. Moss and Russell, op. cit. pp. 164-165
  65. Moss and Russell, op. cit. p.166
  66. "An image intensifier operates at the same wavelength as the human eye as well as near infrared and exploits ambient light from the stars and the moon to enhance vision". (Maritime Defence, Periscopes and optronic masts, Volume 20, Issue 2, 1995)
  67. GUA EGD 295/26/1/69 A drawing dated 28 August 1925 titled 'Trainer's Periscope CL3'survives although whether the nomenclature 'Trainer's refers to the Perisher Teacher or an Attack Teacher is not clear.
  68. Other navies, however, persist with laser range findings. For example, the Kollmorgen and Zeiss periscopes.
  69. Moss and Russell, op. cit. p. 165
  70. Brown, Louis, Technical and Military Imperatives: A Radar History of World War II, Abingdon, Taylor & Francis, 1999, p. 347
  71. TNA ADM 1/22336 Periscope coatings
  72. TNA ADM 1/25613 Radar camouflage of submarine snort masts and the periscopes
  73. TNA ADM 1/25613 Radar camouflage of submarine snort masts and the periscopes
  74. TNA ADM 1/11764 Inventions of Mr. Victor Stohanzel (Austrian) Apparatus for reduction of periscope feather
  75. Thermal imaging also needs a germanium window and cooling, adding to the complexity of the periscope. The thermal imager operates in the infrared band typically between 3-5 or 8-12 μm
  76. Moss and Russell, op. cit., p. 219
  77. Thales: 100 years op. cit.
  78. Email correspondence with Alan Rae January 2018
  79. Thales: 100 years op. cit.
  80. Thales: 100 years op. cit.
  81. GUA UGD 295/27/2/17 Periscopes for the 80's, a Barr and Stroud marketing brochure
  82. Maritime Defence, Periscopes and optronic masts, Volume 20, Issue 2, 1995, p. 36 The American Kollmorgen periscopes use a hydrodynamic fairing whereas the German Zeiss periscopes use gyro stabilisation.
  83. The acronym was an unwieldly EONHPM but the masts are more commonly called Optronic.
  84. The Americans call it a Photonics mast.
  85. Simpson, George, Periscope View, Barnsley, Seaforth, 1972, p.45
  86. Woodward, Admiral Sandy, One Hundred Days, London, HarperCollins, 2003, P.56
  87. Simpson, op. cit. p.167
  88. A term that comes from, principally, the Blyth Attack Teacher which had a revolving control room in which it was very easy to lose orientation.
  89. Macpherson, Martin, Perisher: The Making of a Submarine Commander in 100 Years of The Trade, edited by Martin Edmonds, Lancaster, CDISS, 2001


Secondary Sources

  • Akermann,Paul, Encyclopaedia of British Submarines 1901-1955, Penzance, Maritime Books, 1989
  • Bacon, Admiral Sir Reginald, From 1900 Onward,, London, Hutchinson, 1940
  • Brown, Louis, Technical and Military Imperatives: A Radar History of World War II, Abingdon, Taylor & Francis, 1999
  • Carr, William Guy, By Guess and By God, London, Hutchinson, 1930
  • Churchill, Winston S, Companion Volume II Part 2, London, Heineman, 1969
  • Compton-Hall, Richard, Submarine Boats: The beginnings of underwater warfare, London, Conway, 1983
  • Domville-Fife and Hopkins, Charles William and Ommaney, Submarines of The World's Navies, London, Frances Griffiths, 1911
  • Evans, AS, Beneath the Waves, London, William Kimber, 1986
  • Mackay. Roddock F, Fisher of Kilverstone, Oxford Clarendon Press 1993
  • Macpherson, Martin, Perisher: The Making of a Submarine Commander in 100 Years of The Trade, edited by Martin Edmonds, Lancaster, CDISS, 2001
  • Maritime Defence, Periscopes and optronic masts, Volume 20, Issue 2, 1995
  • Merrill, John, Looking around: a short history of submarine periscopes, Southington, CT, Strong Books, 20021
  • Moss and Russell, Michael and Iain, Range and Vision: The First Hundred years of Barr & Stroud, Edinburgh, Mainstream, 1988
  • Poluhowich, John, The Argonaut: Submarine Legacy of Simon Lake, College Station, Texas A&M University
  • Press Scientific American, Who invented the Periscope?, 16 March 1916
  • Sambrook, Stephen C, The Optical Munitions Industry in Great Britain 1888-1923, London, Pickering and Chatto, 2013
  • Simpson, George, Periscope View, Barnsley, Seaforth, 1972
  • Sisson, George M, Mirror Images in Vistas of Astronomy, 1992, Volume 35
  • Woodward, Admiral Sandy, One Hundred Days, London, HarperCollins, 2003
  • Thales: 100 years of submarine visual system innovation, a booklet printed in 2017 to celebrate 100 years of the company supplying periscopes to the Royal Navy.
  • The Spectator, The recent trials of the new French submarine boat 'Morse', 12 January 1901

National Archives

  • ADM 1/11764 Inventions of Mr. Victor Stohanzel (Austrian) Apparatus for reduction of periscope feather
  • ADM 1/22336 Periscope coatings
  • ADM 1/25365 Further notes on sub sights through a periscope
  • ADM 1/25613 Radar camouflage of submarine snort masts and the periscopes
  • ADM 1/8635/17 Submarine periscopes for the French Navy
  • ADM 186/42 Bacon's Service Record
  • ADM 116/4586 Submarine General Memorandum number 78 dated 30 October 1942
  • ADM 204/648 Cleaning of optical glass surfaces
  • ADM 212/90 Photography through a submarine Periscope
  • ADM 220/1080 Trials of experimental submarine periscope radar ranging system in HMS Fleetwood GUA
  • T 173/725 Claim of Lieutenant Commander FL Newhouse in respect of desiccators for submarine periscopes

Royal Navy Submarine Museum

  • BR 3053, Chapter 22, 22.3 Periscopes

University of Glasgow Archive

  • UGD 295/26/1/24 Letter from Barr and Stroud to the Director of Navy Contracts dated 8 February 1929
  • UGD 295/26/1/26 A Short History of the Early Years of Barr and Stroud Ltd. by F T Gerstenberg
  • UGD 295/26/1/69 Tables, observations, notes, lists and photographs of submarine periscopes 1916-64;
  • photocopied pages describing development of Barr and Stroud into 1970s
  • UG D 295/26/1/70 Orders, reports, observations, tables concerning submarine periscopes and rangefinders
  • (1916-circa 1927). Also, copies of pamphlets 228 and 1170 (Periscope R-F, FT1and CL9)
  • UGD 295/26/1/87 Incomplete MSS of Dr. Strang's History of Barr and Stroud with notes and corrections
  • UGD 295/27/2/17 Marketing brochures


I am indebted to Alan Rae of Thales for his advice, and encyclopaedic knowledge of Barr & Stroud, Pilkington and Thales..


FY 1 1916 First range finder
CH 1 1917 Unifocal
CH 2 1917 Bifocal (skysearching)
CH 3 1917 Unifocal
CH 4 1917 Bifocal (skysearching)
CH 5 1918 Bifocal (skysearching) (Redesign of CH 2) Unifocal with range/inclination estimator
CH 7 CH 4 converted to carry bifocal attacking gear, range estimator
CH 8 Look out bifocal skysearching with roll top prison, top diameter 7.8 inches
CH 9 Unifocal, top diameter 5 inches
CH 21 1926 Bifocal
CH 22 1926 Redesign of CH 13 (French Navy bifocal periscope) 300 mm Well
CH 27 1926 Torpedo Director bifocal skysearching with range estimator
CH 28 1926 Line in space gear and torpedo director
CH 29 1926 Bifocal skysearching periscope (10° depression, 100° elevation)
CH 30 1927 Redesign of CH 23 (French Navy bifocal periscope)
CH 31 1927 Redesign of CH 24 (French Navy periscope)
CH 34 1929 Commander type
CH 35 1929 Zenith type
CH 36 1930 Attack
CH 37 1930 Navigational with range and inclination estimator and line in space gear
CH 40 1931 Bifocal, Swordfish Class
CH 42 1932 Bifocal attack (spherical top)
CH 50 1935 Unifocal
CH51 1935 Attack
CH55 1936 Bifocal attack
CH 57 1940 Unifocal (redesign CH51)
CH 58 1940 Bifocal (redesign CH55)
CH 61 1941 Bifocal skysearching night periscope (redesign of CH 50)
CH 62 1941 "Varley" Class bifocal sky searching
CH 65 1942 X Craft, bifocal attack
CH 66 1943 A Class
CH67 1948 T Class conversion bifocal attack with sextant
CH 68 1951 Midget submarine bifocal attack
CH 70 1953 Bifocal
CH 71 1956 Bifocal new design
CH 72 1956 Bifocal new design
CH73 1956 A Class bifocal attack
CH 74 1958 Oberon Class bifocal attack
CH75 1959 Dreadnought and Valiant Class bifocal attack
CH 76 1959 COQC bifocal attack
CH 78 1964 Resolution Class attack with radar and II
CH 79 Swiftsure Class
CH 80 Prototype laser range finder with stabilised top prism
CH 82 Prototype thermal imaging
CH 83 1973 Swiftsure Class (modified CH79) quasi/binocular attack, TI and AVT, TV camera
CH 80 Trafalgar Class's because I/binocular attack, TI, electronics AVT and TV camera
CH 85 1980 Upholder Class's bi-ocular attack
CH 91 Vanguard Class
CK 1 1924 Binocular
CK 2 1927 Skysearching binocular
CK 3 1928 Parthian Class
CK 4 1929 Bifocal binocular RN Tank periscope
CK 5 1930 Thames Class bifocal binocular
CK 6 1930 Swordfish Class bifocal binocular
CK 7 1935 Bifocal binocular
CK 8 1935 Bifocal binocular
CK 9 1936 Bifocal binocular
CK 10 1942 Bifocal binocular (training gear omitted)
CK 11 1942 Bifocal binocular (training gear omitted)
CK 12 1943 Bifocal binocular (rising top prism)
CK 13 1943 Bifocal binocular night (rising top prism)
CK 14 1943 A Class bifocal binocular night
CK 15 1947 Combined night/radar
CK 16 1949 Bifocal binocular night
CK 17 1952 T Class conversion bifocal binocular night (with waveguide)
CK 18 1952 A Class bifocal binocular night (to replace CK14)
CK 20 1953 Combined night/radar (similar to CK17)
CK 22 1956 Bifocal binocular night (prototype new design)
CK 23 1956 Prototype new design
CK 24A 1956 Bifocal binocular night
CK 20A 1956 Porpoise/Oberon bifocal binocular
CK 24 1958 Oberon Class bifocal binocular night
CK 25 1958 Dreadnought /Valiant Class photographic
CK 26 Swiftsure Class bifocal binocular
CK 28 1964 Resolution Class photographic/sextant
CK29 Swiftsure Class bi-ocular photographic
CK 33 Swiftsure Class modified CK29 for Morthoe
CK 34 1973 Trafalgar bi-ocular, AHPS IV, Morthoe, AVS, 10inch main tube
CK 35 1980 Upholder Class's (modified CK34)
CK 51 Vanguard Class self-protection mast
CM 010 2000 Astute Class's Optronic mast

Barr and Stroud have also supplied periscopes to Australia, Brazil, Canada, Chile, Denmark, Estonia, France, Greece, Italy, Japan, Latvia, Netherlands, Pakistan, Poland, Portugal, South Korea, Spain, Sweden, USA, Yugoslavia

Tables produced by kind permission of Barr and Stroud



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The History Of The Submarine Attack TeacherPeriscopes