John Eissler (1873-1962) was born in Philadelphia in the United States. After having finished his artistic education at the School of Industrial Art in Philadelphia, at the age of 15, he started engraving with Charles H Elliott Co of that same city. In 1900, his decade-long stint at the Philadelphia branch of the ABNC started, and in September 1911 Eissler came to work for the Bureau of Engraving and Printing. There, his philatelic career began.
You will find John Eissler's database HERE.