The Search for Latitude

Antonio de Ulloa y de la Torre-Guiral lay unconscious on the mountainside. ‘I fell down’, he wrote later, ‘and remained a long time without sense or motion; and, as I was told, with all the appearances of death.’

The year was 1737 and the twenty-one-year old naval lieutenant was one of a twelve-man team of scientists who had sailed from Europe two years earlier on a quest to measure latitude. More precisely, they intended to measure the length on the ground of one degree of latitude, at the equator, then compare the figure with one degree of latitude measured in northern Europe. The result would define for the first time the true shape of the earth. To achieve the equatorial measurements, the scientists had to set up surveying stations on a series of mountaintops spanning over two hundred miles. The first difficult mountain they encountered was a volcano called Pichincha; the ‘Vesuvius of Quito’.

Pichincha’s peak was like the point of a needle. Ulloa was appalled:

‘Our first scheme for shelter and lodging, in these uncomfortable regions, was, to pitch a field-tent . . .  but on Pichincha this could not be done, from the narrowness of the summit; and we were obliged to be contented with a hut, so small, that we could hardly all creep into it.’

A small tent was erected in a gap between rocks and into this crammed the five servants. The hired porters opted to sleep lower on the mountain, in the cave.

Outside the hut, they erected the quadrant on its iron stand and waited for the skies to clear so that they could measure the angles between signals set up on adjacent mountains. Young Ulloa, who had survived countless storms at sea, found himself mesmerised by their predicament:

‘When the fog cleared up, the clouds, by their gravity, moved nearer to the surface of the earth, and on all sides surrounded the mountain to a vast distance, representing the sea, with our rock like an island in the centre of it . . .  But our circumstances were very different when the clouds rose; their thickness rendered respiration difficult; the snow and hail fell continually, and the wind returned with all its violence; so that it was impossible entirely to overcome the fears of being, together with our hut, blown down the precipice on which edge it was built, or of being buried under it by the daily accumulation of ice and snow.’

Inside the hut, the men lay on a floor of packed straw, struggling to stay warm. They subsisted on boiled rice with bits of meat or chicken. It was so cold that food froze solid unless balanced on top of a chafing dish of hot coals. For drinking water, they had to melt ice and snow. Each morning, the porters left their cave and climbed to the summit of the mountain, then dug away the snow from the front of the hut, unfastened the leather thongs securing the double-hide door, and released the three Europeans from their smoke-filled hovel.

Every day, the scientists peered into the swirling, freezing mists, hoping for a parting in the cloud that would prompt a dash for the quadrant. With every passing night, they became weaker. Inside the hut, the frigid gloom reverberated with coughing. At over 15,400 feet, they were trapped in thin air, wracked by altitude sickness. Their feet swelled and became so tender that heat was unbearable and walking ‘was attended with extreme pain’. Their hands were covered in chilblains. Their lips cracked so severely ‘that every motion, in speaking, or the like, drew blood.’ Whenever the mists did part on Pichincha, banks of cloud obscured one or both of the signals they needed to view with the quadrant. After 23 days on the summit, the trio of scientists and their servants were helped down the volcano to the oxygen-rich sanctuary of Quito.

The episode on Pichincha forced the scientists to adjust their plans and to set up their survey stations at lower, safer altitudes. And this is now the expedition functioned over the coming years, devising new solutions each time a problem became intractable. The problems they had to overcome were formidable. Earthquakes disturbed their instruments. They fell into ravines and rivers. They provoked riots and became entangled in war. One of their number died of disease and another was murdered. They kept running out of money. But their curiosity remained intact. Notebooks filled with new research on quinine and rubber, platinum and gravity. They conducted the first detailed survey of an Inca site. And, ten years after sailing from Europe, the survivors returned home with the number they had sought. Science was never easy.

Nicholas Crane is the author of Latitude: The Astonishing Adventure that Shaped the World, published by Michael Joseph, and is reviewed here.