... MARUKET HERALD. Corn-Exchlange, London, Monday, May 7, 1804. Our fupply of Wheat for this day's Market has been chiefly from .gent and El'ex, nud the quantity not large; fce this day tle'inight, prices have declined about is. per quarter on the fine forts, and rather more on the ordi- nary. Barley and 11Ialt are dull, and Lonmethitig lower. White and GreyPeafe keep up their price, bat Tick ...