27th January 1715

Sir Isaac Newton has his say on a mysterious Guernsey invention

The De Saumarez family has an impressive history – on Guernsey and beyond. James de Saumarez fought alongside Nelson, was honoured as a baron and, 40 years after his death, was memorialised in Delancey Park. Philip de Saumarez also went to sea and, on his return to Guernsey, served as a Jurat until he lost his hearing.

They weren’t the only de Saumarez family members to have a connection to the sea and shipping, though. Henry de Saumarez, the son of the third Baron de Saumarez, John, who had been chaplain to King Charles II, didn’t spend his life on the waves but he had perhaps been inspired by his nautical relatives.

In early 1715 he made a written statement to the Royal Society, later acquired by the British Museum, describing a device he had invented for tracking how far a ship had sailed. Were such a thing to prove accurate, it would greatly aid waterborne navigation, since vessels would be able to plot their precise position on charts showing underwater obstacles and directions to the nearest land.

The invention was a dial which, according to the statement, “will, by correspondence with a small wheel moving under water, and a little bell striking with the said dial, curiously demonstrate the geometrical paces, miles or leagues, which the ship hath run, which, being applied in a proper manner, will be of little or no hindrance to the course or sailing of the ship.”

The invention explained

Effectively, Henry de Saumarez’s invention was a water wheel that rather than turning a stone to grind corn instead turned a dial on the deck of a ship that struck a bell, allowing the crew to count off their progress. By siting the wheel underwater, rather than in the air, they could be sure that it would turn at the same speed as the ship moved forward.

As de Saumarez explained it, “the said wheel shall turn in any depth of the sea so that no storm or rough sea, nor the violent motion of the ship, will alter, hinder, or stop, the regular working thereof; but the swiftness and slowness shall be seen and heard, by the striking of the little dial.”

The matter was referred to the king, George I, who handed it on to the Admiralty who in turn showed it to famed mathematician and physicist Sir Isaac Newton. They asked his advice.

Newton hedged his bets. While he acknowledged that it would be less trouble to track a ship’s progress with such a device “than by the log-line… I am not yet satisfied that the reckoning will be so exact. I have no experience in sea affairs, nor ever was at sea, and therefore my opinion is not to be much relied on, without the opinion of the Trinity-house”.

A log line was a length of rope cast out behind a ship. The speed at which it was drawn into the water was an indication of the vessel’s progress. Trinity House, meanwhile, is the UK lighthouse authority. It was responsible for the construction of Hanois Lighthouse.

Henry de Saumarez attended several meetings with Trinity House and provided it with drawings and models, but the board wasn’t convinced he’d come up with something it could approve. Its members objected on several accounts and, although de Saumarez is said to have countered each objection, it seems that his efforts may finally, after much buck passing on the part of the authorities, have come to nothing.

It is not known what became of the device, which had been lost by the 1840s.