Machine-History.Com

source: [[http://books.google.com/books?pg=PA290&lpg=PA290&dq=%22+bull+wheel%22+%22keg+float%22&sig=idEE0EfPVw0qiIhhEQ8pV73SXYo&ei=2gUdTO_gA4L6lwfU0Z2nDg&ct=result&id=njBLAAAAMAAJ&ots=EvdFASb6Dq#v=onepage&q=%22%20bull%20wheel%22%20%22keg%20float%22&f=false|Popular Mechanics 1920 Volume 34]]