image MS_776_409
Image number: RS.17389
Credit: ©The Royal Society

Lead weights for sounding the depth of the sea without a line or a cord


10 March 1662


Unknown, Artist

Object type

Archive reference number

Manuscript page number




height (page): 320mm
width (page): 200mm


Content object


Design of lead weights with an iron hook.

In 1662, Robert Moray and William Brouncker had experimented with a wooden ball and lead weights designed by Lawrence Rooke (Cl.P/19/7) to measure the depth of the sea by measuring the time it took for a wooden ball to sink and float back up (the lead weight which made the ball sink slipping off the hook as it touched the ground). In March 1663, Brouncker and Moray, with Alexander Bruce, repeated the trial with differently shaped weights in the channel north of Queenborough in March 1663. The results were read to the Royal Society on 18 March 1663 and ordered to be registered.

These images are copied from RBO/2i/215. Another copy can be found at MS/215/093.

This volume is another copy of entries of the first two volumes of the Register Book. It was given to Sir Joseph Banks by G. S. Heales Esquire of Doctor's Common on 31 May 1814.

Object history

At the meeting of the Royal Society on 18 March 1663, ‘The lord viscount Brouncker, Sir Robert Moray, and Mr. Bruce brought in an account of the observations and experiments, which they had lately made upon the river of Chatham; and his lordship promised to add to them some notes of his own. The paper was ordered to be registered’ (Birch 1:208). The account is printed in Birch 1:208-12.

See similar weights shown in Robert Hooke, 'Directions for observations and experiments to be made by masters of ships, pilots and other fit persons in their sea voyages', Phil. Trans. vol. 2, no. 24 (April 1667), 433-48.

Related Fellows

William Brouncker, 2nd Viscount Brouncker of Lyons (1620-1684, British), Mathematician
Robert Moray (1608-1673, British), Natural philosopher

Associated place

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