Seeing Further Read Free Page B

we who know everything tend to forget how little was known. They were starting from scratch. To the extent that the slate was not blank, it often needed erasure.
    Gresham College, home of the Royal Society, 1660–1710.
    At an initial meeting on 2 January their thoughts turned to the faraway island of Tenerife, where stood the great peak known to mariners on the Atlantic trade routes and sometimes thought to be the tallest in the known world. If questions could be sent there (Ralph Greatorex, a maker of mathematical instruments with a shop in the Strand, proposed to make the voyage), what would the new and experimental philosophers want to ask? The Lord Viscount Brouncker and Robert Boyle, who was performing experiments on that invisible fluid the air, composed a list:
‘Try the quicksilver experiment.’ This involved a glass tube, bent into a U, partly filled with mercury, and closed at one end. Boyle believed that air had weight and ‘spring’ and that these could be measured. The height of the mercury column fluctuated, which he explained by saying, ‘there may be strange Ebbings and Flowings, as it were, in the Atmosphere’ – from causes unknown. Christopher Wren (‘that excellent Mathematician’) wondered whether this might correspond to ‘those great Flowings and Ebbs of the Sea, that they call the Spring-Tides’, since, after all, Descartes said the tides were caused by pressure made on the air by the Moon and the Intercurrent Ethereal Substance. Boyle, having spent many hours watching the mercury rise and fall unpredictably, somewhat doubted it.
Find out whether a pendulum clock runs faster or slower at the mountain top. This was a problem, though: pendulum clocks were themselves the best measures of time. So Brouncker and Boyle suggested using an hourglass.
Hobble birds with weights and find out whether they fly better above or below.
‘Observe the difference of sounds made by a bell, watch, gun,
& c.
on the top of the hill, in respect to the same below.’
    And many more: candles, vials of smoky liquor, sheep’s bladders filled with air, pieces of iron and copper, and various living creatures, to be carried thither.
    Opposite & Previous Page:

A record of the founding of the Royal Society and the first meeting, 28 November 1660.
    A stew of good questions, but to no avail. Greatorex apparently did not go, nor anyone else of use to the virtuosi, for the next half-century. Then, when Mr J. Edens made an expedition to the top of the peak in August 1715, he was less interested in the air than in the volcanic activity: ‘the Sulphur discharging] its self like a Squib or Serpent made of Gun-powder, the Fire running downwards in a Stream, and the Smoak ascending upwards’. He did wish he had brought a Barometer – the device having by now been invented and named – but he would have had to send all the way to England, and the expense would have come from his own pocket. Nonetheless he was able to say firmly that there was no truth to the report about ‘the Difficulty of breathing upon the top of the place; for we breath’d as well as if we had been below’.
    Opposite:

Portrait of Robert Boyle by Johann Kerseboom.
    No one knew how tall the mountain was anyway, or how to measure it. Sixteenth-century estimates ranged as high as 15 leagues (more than 80,000 metres) and 70 miles (more than 110,000 metres). One method was to measure from a ship at sea; this required a number for the radius of the Earth, which wasn’t known itself, though we know that Eratosthenes had got it right. The authoritative
Geographia
of Bernhardus Varenius, published in Cambridge in 1672 with Isaac Newton’s help, computed the height as 8 Italian miles (11,840 metres) –
‘ quae incredibilis fere est’
– and then guessed 4 to 5 miles instead. (An accurate measurement, 3,718 metres, had to wait till the twentieth century.) But interest in Tenerife did not abate – far from it. Curiosity about remote lands was always honoured