In the first decade of the 20th century the American engineers William Merriam Burton and Robert E. Humphreys independently developed and patented a similar process as U.S. patent 1,049,667 on June 8, 1908.
U prvom desetljeću dvadesetog stoljeća, američki inženjeri William Merriam Burton i Robert E. Humphreys, neovisno jedan o drugome, razvili su i patentirali sličan proces kao U.S. patent 1,049,667, 8.