Eight autograph letters by William Herschel, addressed to fellow astronomers Edward Pigott (7 letters) and John Goodricke (1 letter). The letters by Herschel discuss the power of Pigott's telescope, a reading by Pigott at the Royal Society on the meridian observations of Mercury, a spot seen on Mars, observations of the Sun, a recent discovery of a comet by Pigott, and a forthcoming visit from Pigott. They also discuss a meeting between Herschel and Joseph Banks in London on May 4, 1783. The letter to Goodricke thanks him for a recent paper on Mars. There is other discussion of telescopes, periodical stars, etc., and also a small diagram by Herschel. There are also three items with illustrations of Herschel and fellow scientists Edward Jenner, Sir Humphry Davy, and John Hunter.