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John Ross's deep sea instruments (1818)

posted 21 Feb 2019, 05:12 by Historie van de Oceanografie Club   [ updated 21 Feb 2019, 05:14 ]

The plate comes from John Ross’s ‘A voyage of discovery: made under the orders of the Admiralty, in His Majesty's ships Isabella and Alexander, for the purpose of exploring Baffin's Bay, and inquiring into the probability of a North-West Passage’, Vol.2, (2nd edition), 1819. Longman, London. It depicts three instruments used by the expedition: a Deep Sea Clam (Fig. 1), a Hydraphorus (Fig. 2) and a Marine Artificial Horizon (Fig. 3).

The Deep Sea Clamm was an early grab sampler (sounder) designed by Sir John Ross (1777–1856) on board H.M.S. Isabella in 1818. Ross wrote: “The instrument was made from the model by the ship’s armourer, and succeeded on the first trial”. The Clamm worked well and collected sediment as well as some biota (worms, and starfishes attached to the cable) from depths at over 1,000 fathoms. A bonus was that they could, once the instrument was on deck, insert a thermometer in the soft sediment and read a reasonably accurate temperature (in contrast to the non-insulated water samplers). Because of the weight of sampler and cable, the Clamm required a whale line “which are two and a half inches in circumference, made of the best hemp, and very pliable and easily coiled”. For shallower seas Ross advised: “for the North Sea, I would recommend one of fifty pounds”.


Also the Hydraphorus was an invention of John Ross (Appendix XIII opus. cit.). The water sampler he received from Sir Humphrey Davy for the work on board H.M.S Isabella failed “as its power was limited to 80 fathoms”. The new instrument, only manufactured after the return of the ship, was made of copper. The top part had an aperture to let the water in, which was covered by a circular plate with a similar hole and with a toothed rim (800 divisions). This plate was rotated by a vane when lowering the device in the water. Pre-setting of the desired water depth where the sampler should operate was thus possible. 

Its size “intended for the expedition was 18 inches in length besides the swivel, the circumference of the cylinder 15½ inches, the whole weighing 78½ pounds, and intended to contain about 3 English pints of water.”
See e.g. McConnell, 1982[1]; Deacon, 1997[2]
Kees Kramer


DESCRIPTION. FIG. 2.

F — Section of the machinery.

G — Upper part or rope of the instrument.

E — The instrument complete.

No. 5 - Vanes of the rotator.

6 - Rotator with spiral wheel.

7 - First large wheel turned by the rotator.

8 - Small wheel on the same axis, a. No. 7.

9 - Second large wheel turned by No. 8.

10 - Swivel to which the rope is attached.

11 - Spring air valve.

12 - Aperture in the wheel coinciding with one in the cylinder to admit water.

13 - The ears for attaching additional weights.

14 - Stop cock.

15 - Rope.


[1] McConnell, A., 1962. No sea to deep. The history of oceanic instruments. Adam Hilger, Bristol, pp.162

[2] Deacon, M., 1997. Scientists and the sea 1650-1900. A study of marine science (2nd Ed). Ashgate, Aldershot, pp. 459

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