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Story: Charting the sea floor

Depth-recording equipment

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Depth-recording equipment

These sounding devices were used by the Challenger, which surveyed New Zealand waters in 1874. Sounding equipment served two functions – the first and most important was to gauge the depth beneath a vessel. This was done by lowering a weight to the sea floor and measuring the length of the rope or sounding line. A secondary function was to determine whether the seabed below was rocky, sandy or muddy.

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Museum of New Zealand Te Papa Tongarewa

Reference: C. W. Thomson, The voyage of the ‘Challenger’: the Atlantic. Vol 49. London: Macmillan, 1877, p. 2

Permission of the Museum of New Zealand Te Papa Tongarewa must be obtained before any re-use of this image.

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How to cite this page

Lionel Carter, Charting the sea floor – Evolution of modern charting, Te Ara – the Encyclopedia of New Zealand, https://teara.govt.nz/en/artwork/5957/depth-recording-equipment (accessed 5 June 2026).

Story by Lionel Carter, published 2 March 2009.