Obadiah Poundage has been used for information on the types of beer made from what?
Obadiah Poundage:  The letter was reprinted in various journals, including the "Gentleman's Magazine" and "The Gazetteer", and has since been used by beer historians for the basis of information about porter. Porter (beer): Porter is a dark style of beer developed in London from well-hopped beers made from brown malt.
brown malt