麻豆传媒

In July 1802, astronomer William Herschel and his family left their home in England for a holiday in Paris. For two weeks, the Herschels did the sights, went to the opera and admired the city鈥檚 paintings and statues. None of which would be at all remarkable, except Britain had been at war with France for 1O years. But that March, a peace treaty had been agreed, triggering a rush for the continent. Herschel planned to see some of the leading lights of French astronomy. Their telescopes might not be as good as his, but they were better at maths and more than once they鈥檇 come to his rescue when he got his calculations wrong. The war had played havoc with their correspondence, but at last he could see them in person. When Herschel wasn鈥檛 sightseeing, he was engaged in a frantic social whirl. And to round off the holiday, on a hot August day, Herschel talked stars and ate ices with the most famous man in Europe, Napoleon Bonaparte.

THE ink was hardly dry on the Treaty of Amiens when travellers from England began streaming across the Channel. William Herschel was as keen to see Paris as anyone. Months earlier, at the first sign of peace, he had written to tell his French friends he would soon be visiting.

Ten years of war had done nothing to sour Herschel鈥檚 relations with the enemy鈥檚 most eminent astronomers. They had written intermittently and in 1801, with the countries still at war, a letter brought news that the French had elected Herschel to the Institut de France 鈥� the highest honour for a scientist. Herschel and his French friends had a lot of catching up to do. Since discovering the planet Uranus 21 years earlier, he had spent his nights systematically scanning the sky with the telescopes he had built, looking for nebulae and star clusters: so far he had found around 2500. He had also discovered several moons, infrared radiation and determined the motion of the solar system.

On 13 July, Herschel, his wife Mary and their 10-year-old son John, together with Mary鈥檚 niece Sophia, left the family home in Slough and headed for the port of Dover. There they dithered: the sea looked unpleasantly rough. Three days later they finally boarded a packet boat. The day had 鈥渁ppeared to be remarkably fine鈥�, Herschel wrote to his sister Caroline. 鈥淏ut when we came out to sea it proved very windy.鈥� His wife, along with the other women aboard, were so seasick they went below to lie down 鈥渓ike dead folks鈥� while he 鈥渓aid flat upon the ground upon deck and did not stir, tho鈥� a great deal of water dashed over me.鈥�

Three hours later they were in France and on their way to Paris. The party reached the capital on 24 July and for the next two weeks Herschel mixed sightseeing with science. He strolled the city鈥檚 gardens, admired its monuments and went to see the space where the notorious Bastille had stood until recently. He went to the observatory to inspect its telescopes and attended sessions at the institute. He breakfasted, lunched and dined with the leading lights of science and society. And finally, Herschel met Napoleon.

At 7 pm on 8 August, a searingly hot Sunday, Jean Antoine Chaptal 鈥� chemist, industrialist and gunpowder manufacturer to the revolution, and now minister of the interior 鈥� took Herschel to Malmaison, Napoleon鈥檚 palatial Paris home. Napoleon had seized power in a military coup in 1799, replacing the revolutionary government with a consulate and appointing himself first consul. He was a soldier who had fought for the revolution, fought the English and now usurped the place once occupied by the French king. Herschel, the musician-turned-scientist, was the English king鈥檚 hired man. He was paid an allowance by George III and was regularly invited to court to show the royal family the wonders of the night sky. What did the two men find to talk about?

鈥淢aths was one of Napoleon鈥檚 strong points. He even devised a theorem to solve a problem of triangulation鈥�

Plenty, if you believe what Herschel wrote in his diary. Napoleon was passionate about knowledge. He had famously taken almost 200 鈥渟avants鈥� on his military campaign in Egypt, where they studied the country鈥檚 history and culture, its geography and science. He encouraged both arts and sciences. Like Herschel, he had been elected to the Institut de France 鈥� and not because of who he was. 鈥淗e was elected in 1797 when he was not especially influential,鈥� says Peter Hicks, of the Fondation Napoleon in Paris. 鈥淗e was very keen to be elected and he had to write a paper on mathematics to get in.鈥� Napoleon had trained in the artillery, and maths was a strong point. He had even devised a theorem to solve a problem of triangulation. 鈥淗e went assiduously to meetings and followed the debates,鈥� Hicks says.

Chaptal and Herschel found Napoleon in his garden, directing works on an irrigation system for the plants. 鈥淭he first Consul addressed himself to me in politely asking some questions relating to astronomical subjects鈥� After about half an hour鈥檚 walk, he led us towards the house, but stopping short, on meeting some other gentlemen, he entered into conversation with them on the subject of a canal which is to be made in France. The Consul seemed to be perfectly acquainted with the subject.鈥� Napoleon, he reported, could hold his own whatever the topic.

Indoors, Napoleon sat down and invited Herschel to join him. Herschel was uneasy: liberated the French might be but there wasn鈥檛 much sign of 茅驳补濒颈迟茅 here. No one else was invited to sit. 鈥淚 bowed my thanks for the Consul鈥檚 great civility and kept standing with the rest. The first Consul then asked a few questions relating to Astronomy and the construction of the heavens to which I made such answers as seemed to give him great satisfaction.鈥� When Napoleon asked similar questions of fellow guest Pierre-Simon Laplace, the leading theoretician of the age, he had 鈥渁 considerable argument with him鈥� over whether nature or God kept the stars and planets in their place. The conversation turned to less controversial subjects 鈥� the way the English bred their horses, the poor standard of the London police and the liberties taken by the English press. The arrival of ices helped to cool tempers.

A week later, the Herschels were back in England. Within nine months, the two countries were again at war. People at home were curious about Napoleon. What had Herschel made of him? His diary records only the bare facts and he was reluctant to offer opinions. This is no surprise, says Emily Winterburn of the Royal Greenwich Observatory and an expert on the Herschel family. Herschel was careful what he said in public. He had spent years cultivating his image as a self-made man and high-minded seeker of knowledge 鈥� a quest far above politics. All this was something of a front, says Winterburn. He was ambitious and more than once rewrote the story of his life to create a better impression. When it came to Napoleon, he had to be diplomatic. 鈥淗e couldn鈥檛 afford to upset his patron and the upper-class clique that ran the Royal Society. But he wanted to keep in with his French friends.鈥�

Herschel might have had republican leanings. 鈥淗e was close to members of the Lunar Society who were all quite pro-revolution. He seems to have been more comfortable with them than the aristos of the Royal Society,鈥� she says. 鈥淏ut he kept very quiet about his own politics.鈥� Despite this, he gave the impression he was amazed by Napoleon鈥檚 astronomical knowledge.

In 1813, the poet Thomas Campbell visited Herschel and asked him about his notorious interview with the dictator. Times had changed. Napoleon was now emperor and had been at war with Britain for a decade. Herschel鈥檚 reputation was secure and he no longer felt it necessary to court the French. So had Napoleon astonished him with his knowledge of astronomy as people said, Campbell asked. 鈥溾�楴o,鈥� he said, 鈥榯he First Consul did surprise me by his quickness and versatility on all subjects; but in science he seemed to know little more than any well educated gentleman鈥� His general air,鈥� he said, 鈥榳as something like affecting to know more than he did know.'鈥�