It would seem that Robert Schrader gleaned the idea for his drilling from German patent agent W. Stercken(engineer??), who had an idea in the mid 1890s. But Elmore Adelbert Harris of Norwich, Conn. under U.S. of A. patent 394691 may have been the 1st with the overall idea for Robert Schrader's design:

http://www.google.com/patents?id=Z_5CAAAAEBAJ&printsec=abstract#v=onepage&q&f=false

Dr. Moog suggests that Robert Schrader may have sourced E. Schmidt & Habermann.

Kind Regards,

Raimey
rse