Design patent # D4,097, June 7, 1870 by Ludwig Kruezinger.  Originally manufactured by Metallic Compression Casting Company of Boston, and later by Russell & Erwin Manufacturing of New Britain.  Featured in the 1875 R&E catalog.  3 inch plus diameter for $8 a pair.  Deep relief. Marked MADE BY RUSSELL AND ERWIN MFG. CO. on rear. Knob and rose shown on page 376 of the 1875 catalog. Rose design patent # D4119, June 7, 1870 by Joseph A. Ruff.  These are two of 63 design patents issued to MCCCo/ R & E on that date. Earlier examples marked MFD. BY METALLIC COMPRESSION COMPANY R.E. MFG. CO. SOLE AGTS.