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The Determination of Distance at Sea by Vertical Angle

Published online by Cambridge University Press:  18 January 2010

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The very interesting short note by Cotter in the July issue of the Journal is of importance in the history of survey methods used in charting the harbours of East Africa and the delta of the Zambezi. In my researches into the achievements of the Zambezi Expedition of 1858, I finally found in Francis Owen's book that the vertical angle method had been used in 1820 and also in the voyages of Leven and Barracouta from 1821 to 1823. In 1820 Captain W. F. M. Owen in collaboration with the staff at Woolwich calibrated rockets in order to measure distances at sea.

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Copyright © The Royal Institute of Navigation 1972

References

REFERENCES

1Owen, W. F. M. (1833). Narrative of Voyages to Explore the Shores of Africa, Arabia and Madagascar performed in H.M. Ships Leven and Barracouta. London, Bentley, Vol. I, p. 242 and Vol. II, p. 420.Google Scholar
2Becher, A. B. (1854). Tables of Masthead Angles for fire feet intervals from 30 to 208 feet and varying distances from a cable's length to four miles. London, J. D. Potter.Google Scholar
3Raper, H. (1842). The Practice of Navigation and Nautical Astronomy, 2nd edition.Google Scholar
4Belcher, E. (1835). A Treatise on Navigation, containing an outline of the duties of the Naval Surveyor with cases applied to naval evolutions and miscellaneous rules and tables useful to the seaman or traveller. London, Pelham Richardson.Google Scholar