European Heating Systems, circa 1907
Thanks to Frank "Steamhead" Wilsey for finding and sharing these pages from 1907. He tells us, "This is the earliest Orifice system, patented sometime prior to 1901 by Frederic Tudor. Also known as the French or German system since it was popular there. We've seen four of these in Baltimore." And thanks to Gerry Gill for providing us with Mr. Tudor's patents.