Biographies
Caroline Herschel (1750 – 1848)
“I am nothing, I have done nothing at all; all I am, all I know, I owe to my brother. I am the only tool which he has shaped to his use – a well-trained puppy-dog would have done as much” – Caroline Herschel
These modest words are by Caroline Herschel who was the first woman scientist and astronomer to be elected to the Royal Society. She was also honoured by the Royal Irish Academy and awarded the Gold Medal for Science by the King of Prussia. Caroline recognized the importance of her brother’s work, and in 1772 she left Hanover volunteering to come to Bath as his housekeeper and assistant. She had good voice and sang at concerts at many musical venues in the city, and could have probably become a professional musician. However, she relinquished this ambition as William’s astronomical career proceeded. William trained Caroline in the basics of mathematics and astronomy and made her a small telescope which she used to sweep the sky for comets. In 1798 Caroline produced the index to Flamsteed’s Star Catalogue, the first of several such projects. Perhaps our greatest debt to her however, is the meticulous recording of daily life in Bath and Slough through her memoirs and journals which she wrote in clear English.
Comet Sweeping
Following the discovery of Uranus in 1781 Caroline Herschel became increasingly involved in the science of astronomy. Not only did she help her brother with recording and noting his observations, but she made a significant contribution in her own right. Initially she was given a small refracting telescope by William to enable her to hunt for comets.
“Aug. 1. I have calculated 100 nebulae today, and this evening I saw an object which I believe will prove tomorrow night to be a comet.”
For all his remarkable achievements William Herschel failed to discover a comet, but for many years his sister, Caroline became an avid comet hunter discovering at least eight new ones. Her achievements in this field were recognised by the scientific establishment who awarded her medals and honours at the end of her life.
William Herschel as Musician and Composer
Until the age of 40, William Herschel was a prolific composer. Although much of his music is now lost and much of what is known is rarely performed, his musical repertoire ranged between symphonies, chamber music and choral works. He wrote for instruments as diverse as the organ, flute, cello, viola and harpsichord.
The King and the Astronomer
King George III had a fascination for science, and astronomy in particular. He kept abreast of the latest discoveries and patronized the leading astronomers of the day. When William Herschel made his remarkable discovery of Uranus in 1781, his fame quickly spread and the King was duly impressed. This led to a royal appointment and a grant of £200 a year to pursue his enquiries firstly at the King’s seat, Datchet, near Windsor, and latterly at Slough. In return he was expected to show the Royal Family and their guests interesting astronomical observations. Later the King rewarded Herschel with £4,000 towards the construction of his 40ft telescope as well as a stipend of £50 per annum for Caroline. It is said that during his period of madness King George believed that he could see Hanover through one of Herschel’s telescopes
Herschel’s Telescopes
The key to William Herschel’s success as an astronomical observer was undoubtedly the power and high magnification of his telescopes. At the end of the 18th century the science of telescope making was relatively undeveloped. The refractor models generally used by astronomers of the day collected light through a glass lens which was located in the main tube. For Herschel however refractors were simply not accurate or powerful enough for the massive tasks he set himself. He therefore designed and built his own telescopes, using the reflector principal. This involved a primary mirror with a secondary eyepiece situated on the side of the main tube, which was usually octagonal in shape. Because of the difficulty involved in casting glass mirrors, Herschel favoured speculum metal, an alloy which could be polished to high resolution. Experimentation with mirror casting enabled Herschel to start building telescopes which were much larger than anything previously known. To assist him in his work, he employed cabinet makers, workmen and even his own brothers.
In the reception room of the museum is a full-sized replica of one of the most successful of Herschel’s telescopes, the seven-foot, which is mounted on a wooden stand with a system of handles to adjust the height of the tube. It was with a seven foot model that Herschel made his ground-breaking discovery of Uranus in March 1781.
Larger and more ambitious designs followed with tubes of 10 feet, 20 feet and ultimately 40 feet in length. The great 40 foot telescope built at Slough is described by Patrick Moore as a colossus. It was begun in 1785 and had a sheet metal tube wide enough for visitors to actually walk through it. Unlike other reflectors it had a front view optical system with a single tilted main mirror, but this massive 48 inch mirror proved extremely difficult to cast; several were abandoned as they cracked during the manufacturing process. A complex wooden framework supported the tube and the whole structure rotated on a base with huge ladders leading to an observer’s platform at the top end of the tube. Communication took place through means of a speaking tube linked to Caroline or an assistant in position in a hut on the ground, or to the workmen whose job it was to rotate the structure.
Unfortunately the great 40 foot telescope never lived up to expectations – it was cumbersome to manoeuvre and the mirrors tarnished easily. As a result of these shortcomings it was used infrequently and having been badly damaged in a gale it was later ceremoniously demolished by John Herschel in 1839.