a market town in the Wycombe parliamentary division of Buckinghamshire, England, 18 m. W. of London by the Great Western railway. Pop. of urban district (1901), 11 ,453. It lies in the flat valley of the Thames, nearly 2 m. from the river at Eton and Windsor, and is wholly modern in appearance. The chief public building is the Leopold Institute and Public Hall (1887), a memorial of Prince Leopold, Duke of Albany. The British Orphan Asylum is also in the town. The parish church of Upton-cum-Chalvey, St Laurence, has a Norman doorway and other portions of the same period. It is the burialplace of Sir William Herschel, who lived in the vicinity, set up his great telescope here, and made many of his astronomical discoveries.