Deflection Totaliser

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Deflection Totaliser[1]

A Deflection Totaliser was a component created for the Dreyer Fire Control Table consisting of several handles and geared differentials which permitted spotting corrections, corrected Dumaresq Deflection and other adjustments to be tallied into a gun deflection. Its function largely mimicked the Spotting Corrector's role in handling adjustments required to convert clock range to gun range.

Core Features

The totaliser was an adding machine for various components of gun deflection to be added together. The inputs were:

  • Spotting
  • Drift
  • Wind
  • Dumaresq

The separate inputs each had a dial and a handle to set its value, and on the side of the device a large handle could chase the final sum to send it to the Deflection Master Transmitter on the bulkhead. For convenience, the Spotting column had a resettable index pointer so that successive increments could be precisely added in.

The Drift column was to account for "uncorrected drift", which may have been important if the director were firing with its 6 degree super-elevation prisms shipped, as these would cause the drift correction in use to be that of a range requiring 6 degrees less elevation.In other cases, it might be employed to enter in the small differences between the drift correction offered by the sights in use and the true drift, or when reduced charges were used which caused great differences in drift from that corrected by the sights. These data were possibly read off a table printed on a small card.[Inference]

See Also


  1. Handbook of Captain F. C. Dreyer's Fire Control Tables, 1918. Plate 18.


  • Admiralty, Gunnery Branch (1918). Handbook of Captain F. C. Dreyer's Fire Control Tables, 1918. C.B. 1456. Copy No. 10 at Admiralty Library, Portsmouth, United Kingdom.