"It is a far cry from the facile imaginings of the philosopher to the rigorous demonstrations of exact science, and the true structure of the universe is not yet known.''

George Ellery Hale, 19261

Figure 4.1 Friedrich Wilhelm Herschel (1738-1822). (Credit: National Portrait Gallery, UK.)

The streets of Bath, a fashionable spa town in southwestern England, lay in darkness as Dr. William Watson made his way home one evening in December 1779. As he turned a corner, he caught sight of a curious figure in the gloom: a man standing to the side of a long rectangular wooden tube pointed at the sky (see figure 4.2). The tube rested on a stand in the street, in front of a modest house. It was pivoted near the bottom, and the man appeared to have his head pressed to the side of the tube at the upper end.

Intrigued, Watson drew to a stop. He maintained a respectful silence until the man took his eye off the instrument, a telescope

Figure 4.2 Herschel's 7-foot focal length telescope, of aperture about 6 inches. This was the instrument Herschel was using in 1779 when he met William Watson in the street in front of his house. He was using it in 1781, too, when he discovered the planet Uranus. (Credit: Layne Lundstrom.)

7 feet long and about 6 inches in diameter. Then he begged the favor of a glimpse through the instrument, and in response to a courteous invitation to see the Moon, the observer's object of study, he stepped up to the telescope and approached his eye to the eyepiece, a small cylinder protruding near the top of the tube.

Watson's first reaction was a sense of being dazzled. An intense beam of moonlight—reflected off the curved mirror at the bottom of the wooden tube, intercepted and reflected sideways by a small flat mirror near the top, and funneled through the eyepiece lenses—shone into the pupil of his eye. He blinked in the unexpected glare. At the same time, he exclaimed in admiration as the Moon's cratered surface sprang into focus.

Watson thanked his new acquaintance for sharing his view of this stunning lunar panorama. He returned to the house the next morning to express his gratitude again and to introduce himself properly. The telescope afficionado, he learned, was William Herschel, a professional musician in his early forties. Herschel had made the instrument himself, in his spare time, with help from his brother Alexander and his sister Caroline.2

Watson, the son of an eminent medical doctor and experimenter in electricity, recognized in Herschel a natural philosopher in need of an intellectual circle. Watson himself was a member of the Royal Society in London, and involved with the establishment of a similarly oriented philosophical society in Bath. He invited Herschel to join.

As Watson might have predicted, Herschel's contacts with the society helped him expand the scope of his research and taught him how to present his findings to an educated audience. More importantly, Watson's support helped Herschel make connections with members of the scientific establishment in London. Herschel soon needed their backing. Although neither Herschel nor Watson knew it at the time of their first meeting, the view through Herschel's home-made telescope was superior even to that afforded by telescopes at the Royal Greenwich Observatory. Herschel's skill as an observer and his familiarity with the night sky put him in a class by himself. His curiosity eventually led him to explore the universe as no one had done before. And his first discovery with this telescope—a new planet—challenged the world's leading astronomers to give credit to a relatively unknown amateur.

Herschel (figure 4.1) was born 15 November 1738 in what was then the independent port city of Hanover, Germany. The third of six children, William appears to have been warmly attached to his siblings — his older sister Sophia and brother Jacob, and his younger siblings Alexander, Caroline, and Dietrich. All of them except Sophia remained close to him in adulthood, and lived with him at different times after he settled in England.

William's father Isaac, an oboist in the Hanoverian Guards military band, had little formal schooling, but encouraged all his children's learning. Despite the family's limited finances, he provided tutors so that his sons could study mathematics, languages, and music beyond the level taught at the garrison school they and their sisters attended. Isaac must have read or studied on his own, too, for he relished intellectual discussions with his children. Caroline later recalled impassioned exchanges between him and her brothers: ''Generally their conversation would branch out on philosophical subjects,'' she wrote in a family history. ''[M]y brother William and my father often argued with such warmth that my mother's interference became necessary when the names Leibnitz, Newton, and Euler sounded rather too loud for the repose of her little ones, who ought to be in school by seven in the morning.''3

Each of the four Herschel boys started training for a musical career as soon as he could hold a child-size violin. William's best instruments were the oboe and violin. At 14, he joined his father and Jacob as a bandsman in the Hanoverian Guards. He continued his private studies for a few years, however, having demonstrated exceptional talents in languages and mathematics and a desire to cultivate them. In his own memoir, he recalled that his tutor, a ''man of Science,'' inspired him to study logic, ethics, and metaphysics, and inculcated a love of learning. ''[A]ltho' I loved Music to an excess & made a considerable progress in it,'' he wrote, ''I yet determined with a sort of enthusiasm to devote every moment I could spare from business to the pursuit of knowledge which I regarded as the sov[er]eign Good, & in which I resolved to place all my future views of happiness in life.''4

The tumultuous 1750s did not allow Herschel much time for metaphysics. Europe's so-called ''wars for empire'' pitted the forces of the northern German states and England against those of France, Spain, Austria, Bavaria, Swabia, and Russia. In 1756,

Herschel, his brother Jacob, and his father Isaac were sent to England in anticipation of a French invasion of that country. Yet even under these rough conditions, Herschel seized opportunities to widen his horizons. While encamped in England for the better part of a year, he made the acquaintance of local musical families who were to provide valuable assistance when he and Jacob later returned there to live. And he used what little money he had to buy a copy of the philosopher John Locke's book An Essay Concerning Human Understanding, which articulated the empiricist view so essential to his own scientific outlook, that ideas are not innate but come from experience and reflection.

Early in 1757, the Hanoverian Guards took up new positions on their home territory, and even the bandsmen found their situation precarious as their regiment faced the French in the brutal battle of Hastenbeck. Herschel noted that ''nobody had time to look after the musicians — they did not seem to be wanted.''5 He went home and made plans to leave the country, following his father's admonition to get out of harm's way. His sister Caroline later recalled, ''I can now comprehend the reason why we little ones were continually sent out of the way, and why I had only a chance glimpse of my brother as I was sitting at the entrance of our street-door, when he glided like a shadow along, wrapped in a great coat, followed by my mother with a parcel containing his accoutrements.''6 Because of his youth, Herschel had never formally enlisted in the army, but he had to leave carefully. As added security, he later received formal discharge papers from the Hanoverian King of England, George III.

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