I found a patent assigned to Rollin White describing a multinozzle burner for a boiler. Patent number 1,054,066. filed on September 7, 1907, would that have been around the time of one of the rebuilds of Billy?
Here is the link:
I was wrong about one being in the center of the venturi, he just basically made a coil of vaporizing tubing and drilled 6 holes in it facing the venturi. A very simple yet effective design.