Letter: Letters: Leaning on the past

From C. J. N. TROLLOPE

It is good to see some positive thinking by John Burland of Imperial
College, reported in ‘Pressure mounts to end Pisa’s decline’ (Technology,
21 August). The plan to stabilise the leaning tower of Pisa is, however,
a case of reinventing the wheel. It has all been done before – 183 years
ago in Clacton, when Captain George Whitmore righted Clacton’s Martello
C, a 15-metre tower weighing 3600 tonnes which had suddenly sunk 2 metres
on 18 October 1810.

Martello C was also built on clay and while it was only a quarter of
the weight and height of Pisa’s tower, righting it through 5 degrees was
no small problem. Captain Whitmore achieved it only four months.

He dug a series of holes and trenches 7 metres from the high side. These
he kept drained of water. He hung guns and iron shot on the same high side
and further weighted it with bricks. By manipulating his ground works, filling
some holes and extending others, the problem was solved in four months,
Martello C was straightened and the Napoleonic wars allowed to continue.
The cost was minimal, the thinking brilliant. Martello C still stands level
today, if a little lower than the rest of the towers, and without a crack.

I trust John Burland will have as much success at Pisa, even if he does
have to use more than bucket and spade. It seems today that no job can be
seen to be done properly unless you go ‘hi-tec’ and throw vast sums of
money at it.

C. J. N. Trollope Colchester, Essex