“ On the east lies the open flat valley of the Lea, which flows in several branches, and is bordered, immediately outside the confines of the borough, by the extensive reservoirs of the East London water-works. In these low lands lie the Hackney Marshes (338 acres; among several so-called marshes in the Lea valley) , and the borough also contains part of Victoria Park and a number of open spaces collectively called the Hackney Commons, including Mill Fields, Hackney Downs, London Fields, &c. The total area of open spaces exceeds 500 acres. ”