Friedrich Wilhelm Herschel, (better known to us as William Herschel) was born in Hanover on 15th November 1738. His father was a talented musician and Wilhelm also inherited his musical ability. He secured a knighthood in 1816 for his astronomical achievements. He was born 11 years after Newton's death and he became as famous in his own day as Newton had been earlier. As a mathematician and theorist he could not compare with Newton - nor did he wish to. He was first and foremost an observer, probably the greatest who has ever lived.
In 1757 he came to England and, it is believed, with very little money, in order to make a fresh start. Being a talented musician, however, he had no difficulty in earning his living. Music was never everything to the young Herschel and it was not long before he turned his attention to astronomy, where a good deal of his interest had already been. He enjoyed using a hired small reflecting telescope but as it had insufficient power and he could not afford to purchase a more powerful one, he decided to construct his own. In 1773 he experimented with various mirrors and, after no less than 200 failures, he produced a workable one of 5 inches diameter. His first observation with his new telescope was made of the Orion Nebula. Herschel went on to produce larger and more powerful instruments. Although primarily a stellar observer, he was responsible for discovering Uranus, a planet of considerable size. It proved to have a mean distance from the sun of 1,783,000,000 miles and a diameter of over 29,000 miles. Uranus can just be seen as a naked eye object at just below 5th Magnitude.
Herschel's method was to tilt the main mirror to remove the need for a flat mirror (as with the Newtonian principle) to obviate further loss of light. After studying the Milky Way he came to the conclusion, quite rightly, that this formed part of our galaxy. The only serious error lay in placing the sun in the centre of the system. As we now know, it is situated well out to one side.
If an observer looked along the direction A to B as shown in the diagram below, he or she would see many stars, giving rise to the Milky Way effect, whereas if he looked along the direction C to D, he would see fewer stars. In this respect Herschel's views were perfectly sound.
Having had reasonable results with the new type of reflector, i.e. with the tilting object mirror as opposed to from the Newtonian set

up, in January 1787 he tested a giant instrument with a focal length of 20 feet. He immediately made the discovery that Uranus was attended by 2 satellites. As a result of these findings, he decided to construct an even larger telescope, having a mirror 48 inches in diameter and a focal length of 40 feet. After 3 attempts, a useable mirror was made, weighing 2118 pounds (just under 1

ton). This was slung in a ring and the sheet iron tube in which it rested was 5 feet in width. The whole instrument was mounted in scaffolding on a revolving platform and had ladders for access. The garden of his new home, "Observatory House" in Slough, was large enough to accommodate the enormous telescope and he proceeded to use it only when the visibility was very good. For his more routine work, a smaller instrument was used. It must be borne in mind that atmospheric clarity must have been better than it is now as there was less pollution. It was used for the last time on 19th January 1811, when observations were carried out of the Orion Nebula. This was not before he had made many discoveries such as satellites, comets, etc.
In 1788 Herschel married and his sister, who was always a devoted assistant, moved out of Observatory House, but still continued to help her brother with his work. Most of his observations concentrated on the stars, including binaries and optical doubles etc. In appreciation of his achievements, he was made president of the newly formed Astronomical Society of London. This is now known as the Royal Astronomical Society. His last scientific lecture was presented when he was 80 years old. The Herschels were a long-lived family After Williams death on 25th August 1822, aged 83 years, his sister returned to Hanover and eventually died at the advanced age of 98 years.
Observatory House in Slough was demolished in 1960 after becoming derelict, with the garden overgrown, and it is said that part of the tube of the great telescope was found in a shed nearby when the demolition contractors moved in. Modern shops and flats now occupy the site. Sadly the 1960's were not the best years for the retention of buildings of historic or scientific interest. Perhaps nowadays it would have been a listed building and turned into a museum containing Herschel memorabilia, which would have been a fitting tribute to one of the greatest stellar observers that ever lived.