An intimacy was gradually established between Herschel and Dr. Burney. They saw each other often at the meetings of the Royal Society, and Herschel frequently stayed at the doctor's house. "On the first evening Herschel spent at Chelsea, when I called for my Argand lamp, Herschel, who had not seen one of those lamps, was surprised at the great effusion of light, and immediately calculated the difference between that and a single candle, and found it sixteen to one."[25]
In 1793 we find Herschel as a witness for his friend James Watt, in the celebrated case of Watt vs. Bull, which was tried in the Court of Common Pleas. And from Muirhead's Life of Watt, it appears that Herschel visited Watt at Heathfield in 1810.
A delightful picture of the old age of Herschel is given by the poet Campbell,[26] whose nature was fitted to perceive the beauties of a grand and simple character like Herschel's:
"[Brighton], September 15, 1813.
. . . "I wish you had been with me the day before yesterday, when you would have joined me, I am sure, deeply in admiring a great, simple, good old man—Dr. Herschel. Do not think me vain, or at least put up with my vanity, in saying that I almost flatter myself I have made him my friend. I have got an invitation, and a pressing one, to go to his house; and the lady who introduced me to him, says he spoke of me as if he would really be happy to see me. . . . I spent all Sunday with him and his family. His son is a prodigy in sciences, and fond of poetry, but very unassuming. . . . Now, for the old astronomer himself. His simplicity, his kindness, his anecdotes, his readiness to explain—and make perfectly conspicuous too—his own sublime conceptions of the universe are indescribably charming. He is seventy-six, but fresh and stout; and there he sat, nearest the door, at his friend's house, alternately smiling at a joke, or contentedly sitting without share or notice in the conversation. Any [Pg 108] train of conversation he follows implicitly; anything you ask he labors with a sort of boyish earnestness to explain.
"I was anxious to get from him as many particulars as I could about his interview with Buonaparte.[27] The latter, it was reported, had astonished him by his astronomical knowledge.
"'No,' he said, 'the 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, and of astronomy much less for instance than our own king. His general air,' he said, 'was something like affecting to know more than he did know.' He was high, and tried to be great with Herschel, I suppose, without success; and 'I remarked,' said the astronomer, 'his hypocrisy in concluding the conversation on astronomy by observing how all these glorious views gave proofs of an Almighty Wisdom.' I asked him if he thought the system of Laplace to be quite certain, with regard to the total security of the planetary system from the effects of gravitation losing its present balance? He said, No; he thought by no means that the universe was secured from the chance of sudden losses of parts.
"He was convinced that there had existed a planet between Mars and Jupiter, in our own system, of which the little asteroids, or planetkins, lately discovered, are indubitably fragments; and [Pg 109] 'Remember,' said he, 'that though they have discovered only four of those parts, there will be thousands—perhaps thirty thousand more—yet discovered.' This planet he believed to have been lost by explosion.
"With great kindness and patience he referred me, in the course of my attempts to talk with him, to a theorem in Newton's 'Principles of Natural Philosophy' in which the time that the light takes to travel from the sun is proved with a simplicity which requires but a few steps in reasoning. In talking of some inconceivably distant bodies, he introduced the mention of this plain theorem, to remind me that the progress of light could be measured in the one case as well as the other. Then, speaking of himself, he said, with a modesty of manner which quite overcame me, when taken together with the greatness of the assertion: 'I have looked further into space than ever human being did before me. I have observed stars, of which the light, it can be proved, must take two millions of years to reach this earth.'
"I really and unfeignedly felt at this moment as if I had been conversing with a supernatural intelligence. 'Nay, more,' said he, 'if those distant bodies had ceased to exist two millions of years ago, we should still see them, as the light would travel after the body was gone. . . .' These were Herschel's words; and if you had heard him speak them, you would not think he was apt to tell more than the truth.