S.H. & H. Chapman
The Chapman brothers, Samuel Hudson and Henry, first worked for John Haseltine before joining forces and founding their own firm in 1879. Their 1882 sale of the Bushnell collection demonstrated their capability to attract important consignments and showcase them in an appealing manner. The Chapman brothers parted ways in 1906, for reasons unknown, and operated independently with good success into the 1930s.
Data source: Coinbooks.org