Barr and Stroud Fire Control Instruments

Barr and Stroud manufactured a large and evolving family of step-by-step fire control instruments to convey ranges, deflections, orders and similar information throughout a ship. Over time, the Royal Navy would come to rely on many Barr and Stroud devices, as they edged out competing product lines such as Siemens Fire Control Instruments and achieved a healthy proportion of adoption alongside those of Vickers Fire Control Instruments.

Early Designs

todo: Range and Vision photo p. 35. Part of the Royal Navy's advertisement for workable rangefinding equipment that inspired Barr and Stroud's formation and their main line of business also specified that the rangefinders should be able to instantaneously send their indications. Barr and Stroud delivered range and order instruments in 1894 and refined it over a period of 4 years and started installations on Japanese capital ships.

In 1903, some pointer-and-dial Barr and Stroud instruments were bolted onto plates, the backside of which were fired upon by a Maxim machine gun in bursts of 3-20 rounds in order to ascertain their resilience to shock. There were some failures, but most were simply cases of the transmitter and receiver being put out of step. In some tests, a sledgehammer was used to deliver the shock. No conclusion is stated in the report, but an area of exploration mentioned in the nature of their mounting in order to absorb and reduce shock.

It appears that these early instruments used pointers on dials to display the data. By the Mark I era, however, it was seen as superior for the range receiver to have the dials rotate inside the chassis and have only the proper entry displayed through an aperture. This would have the benefit of allowing the eye to read the components of the range in proximity to each other.

In 1904, reports from ships were uniformly favourable, although a minor adaptation was required in the instruments in London.

Mark I Instruments

Range	0 to 9975 (later 12975) in 25 yard steps
Deflection	50 knots left or right
Orders	3 binary orders, with gong
Rate	in seconds to alter 50 yards
Bearing	Compass Quadrant Bearings in 1/4 degree steps

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The 1904 Annual Report of the Torpedo School outlined a scheme for fire control from primary and secondary control positions which would use Barr and Stroud Mark I instruments for range, deflection and orders. Some problems seem to have arisen, as these first installations used only the Mark I order instruments, though Mark II Barr and Stroud range instruments were substituted for the earlier models. As these installations were being made, other ships received Siemens Fire Control Instruments

Advances and alterations were rapid. By 1908, the Mark I instruments were considered obsolete to the point that the Torpedo Drill Book explicitly declined to describe them.

By 1909, dissatisfaction with the Mark I range instruments was apparent (see below), as the ships were now equipped with Mark II range instruments, Mark I order instruments, and the Vickers deflection instruments. Moreover, King Edward VII and New Zealand a.k.a. Zealandia from the original list were apparently fitted with Barr and Stroud Mark II/II* instruments throughout.

Judging by their pattern numbers, the Mark I rate and bearing instruments seem to have been designed much later than the other Mark I instruments, perhaps being assigned the lower mark number simply because they were the first Barr and Stroud instruments made for these purposes. This apparent practice was continued by the appearance of a modified form of a later Mark's single order instruments as the "Mark I" fall-of-shot instruments first installed in Queen Elizabeth in 1915.

Mark II Instruments

Range	0 to ???? in 25 yard steps
Deflection	?? knots left or right
Orders	1 order selected from menu of 8-10
Rate	0 to 1990 yards / minute, opening or closing, in steps of 10
Bearing	No Mark II instruments? (see Mark II*)

todo: range and vision photo p. 69.

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Initial testing of the new Mark II instruments occurred at Vernon, Excellent and on board Britannia during gun trials. Troubles in getting the transmitter to stop at the desired range was solved by employing a fast and slow speed setting for the handle (100 yards per revolution versus 25 yards).

Competitive testing run by Vernon and Excellent using instruments from Vickers and the Facsimile Syndicate Company showed Barr and Stroud the best overall choice.

The Mark II family introduced the classic pattern of design for Barr and Stroud, centered on cyclometric displays augmented by indicating shutters. A notable improvement in thinking was to agglomerate range, deflection and order indications into a single combined receiver to simplify wiring and produce a more compact arrangement at both ends. However, standalone products for single range, single order and single deflection would continue to be produced through Mark III — perhaps with an eye to updating Mark I ships or simply to provide flexibility. Additionally, the Mark II family included single range instruments and new rate instruments.

Mark II* Instruments

Range	0 to ??? in 25 yard steps
Deflection	?? knots left or right
Orders	1 order selected from menu of 10
Rate	??? yards per minute opening or closing in steps of 25
Bearing	relative bearings in 1/4 degree steps

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These were outwardly indistinguishable from the Mark II instruments, but their internal wiring and brushes differed. The function would have been identical, and the changes were perhaps to enhance problems maintaining connectivity in Mark II plugs — the most common type of failure particular to that series.

The Mark II* family included combination instruments as well as separate instruments for ranges, range rates, orders, and bearings.

As the Royal Navy's thinking on best practices matured, the instruments kept pace: Mark II* bearing instruments differed from those of the Mark I generation by moving to relative bearings from the quaint use of Compass Quadrant Bearings, and the Mark II* rate instruments used steps of 25 yards per minute rather than 10 as had been used in the Mark II instruments.

Mark III Instruments

Range	0 to ??? in 25 yard steps
Deflection	?? knots left or right
Orders	1 order selected from menu of 10
Rate	??? yards per minute opening or closing in steps of 25
Bearing	relative bearings in 1/4 degree steps

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The Mark III family was probably introduced sometime shortly after 1909.

The family included combination instruments as well as some for single ranges, orders, rates and bearings. The range instrument sported some new features that recommended its use for reporting range cuts from rangefinders down to the TS, but generally the differentiating feature was that the external wiring to the instruments was consolidated so all cores would be admitted through a single gland.

Mark III* Instruments

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Not much is known of the Mark III* family. It appears that it included rate instruments and single order instruments, but perhaps no more than that.

Mark IV Instruments

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Appearing during or before 1914, the Mark IV family had rate and bearing instruments, but perhaps no more than that.

See Also

• Siemens Fire Control Instruments
• Vickers Fire Control Instruments
• Barr and Stroud Rangefinders

Bibliography

• H.M.S. Vernon. Annual Report of the Torpedo School, 1903, with Appendix (Wireless Telegraphy). Copy 478 at The National Archives. ADM 189/23.
• H.M.S. Vernon. Annual Report of the Torpedo School, 1904, with Appendix (Wireless Telegraphy). Copy 237 at The National Archives. ADM 189/24.
• H.M.S. Vernon. Annual Report of the Torpedo School, 1906, with Appendix (Wireless Telegraphy). Copy 46 at The National Archives. ADM 189/26.
• H.M.S.O., London Torpedo Drill Book, 1905 (Corrected to December, 1904). Copy in Tony Lovell's library.
• H.M.S.O., London Torpedo Drill Book, 1908 (Corrected to December, 1907). Copy in Tony Lovell's library.
• H.M.S.O., London Torpedo Drill Book, 1912 (Corrected to April, 1912). Copy in Tony Lovell's library.
• H.M.S.O., London (1914). Torpedo Drill Book, 1914 (Corrected to May 15) Copy in Tony Lovell's library.
• Admiralty, Gunnery Branch (1910). Handbook for Fire Control Instruments, 1909. Copy No. 173 is Ja 345a at Admiralty Library, Portsmouth, United Kingdom.
• Admiralty, Gunnery Branch (1914). Handbook for Fire Control Instruments, 1914. G. 01627/14. C.B. 1030. Copy 1235 at The National Archives. ADM 186/191.