I’ve written before about my enthusiasm for Leonardo da Vinci as an exemplar of the fertility of bringing artistic sensibilities to science and vice versa (see “Imagined but not imaginary”). A small exhibition at the Laing Gallery in Newcastle with ten of his drawings from the Royal Collection on display gave me an opportunity to indulge my passion, particularly as it included one drawing that is pertinent to the subject of this blog.
It is an intriguing story because it brings Leonardo together with some of the most notorious names in Renaissance Italy: Cesare Borgia and Niccolo Machiavelli. It was at the court of Cesare Borgia that Leonardo crossed paths with Machiavelli, then the Florentine ambassador, and was later employed by the government of Florence on a grand engineering scheme.
The scheme – which truly deserves the adjective “Machiavellian” – involved diverting the River Arno downstream of Florence in order to deprive their rivals, the Pisans, of the water supply they needed to survive a siege. Later in the same year, he was also commissioned to design a canal to help convey Florentine trade goods to the Mediterranean. The diagram above is one of the maps he drew as part of his preliminary survey of the river and shows the River Arno flowing from left to right.
What is interesting is his depiction of the damage caused by the river at two points on the bank below the weir. The impression from the map is of an artificial embankment on the right bank of the river which is being eroded by the force of the river as it emerges from the weir and then again a short distance downstream as the current describes an arc within the river channel. Called in to advise on “hard engineering”, he deftly points out the folly of working against nature. Like many of Leonardo’s grand ideas, the diversion of the Arno never got passed the planning stages. Ironically, his plans to alter the Tuscan landscape were confounded by changes in the political landscape: the defeat of Pisa by conventional military means and, ultimately, the defeat of Florence and Machiavelli’s fall from power.
I would have noted this drawing and have moved on were it not for an article I had read the same morning in the Independent on Sunday, describing the UK Government’s belated conversion to the importance of soft engineering in the aftermath of the winter floods. Increased spending on flood defence is also a key feature of today’s budget and, whilst a large part of this will, I am sure, be directed towards old-fashioned hard engineering (and, indeed, this will be necessary to protect some towns), I am glad to see that, 500 years after Leonardo, its limitations are finally being recognised by politicians.