Question

During the late eighteenth century, the British monetary system faced a severe crisis due to the proliferation of debased and counterfeit copper coinage. Previous minting methods relied on screw presses operated manually or by horses, which produced coins with inconsistent weights and imprecise edges vulnerable to clipping—the illegal practice of shaving precious metal from a coin's perimeter. In 1788, industrialist Matthew Boulton established the Soho Mint in Birmingham, introducing a revolutionary steam-powered coining press that integrated automated collar dies. Unlike traditional open-die stamping, Boulton’s closed collar mechanism contained the metal blank laterally at the exact moment of impact. This constrained expansion not only guaranteed uniform diameter and thickness across production runs but also simultaneously impressed serrations or lettering onto the coin's edge.

Although contemporaries initially attributed the Soho Mint's success solely to the increased striking power afforded by James Watt’s rotative steam engine, internal mint ledgers reveal that mechanical power alone was insufficient to deter forgery. Counterfeiters could replicate high-pressure strikes using conventional hydraulic fly-presses. Rather, it was the structural synchronization of the collar die with automated feeding mechanisms that rendered illegal replication cost-prohibitive. By ensuring that every coin possessed an unalterable, raised rim and raised edge-inscription in a single motion, Boulton’s apparatus eliminated the secondary, labor-intensive milling step previously required to finish coin edges. Consequently, the Royal Mint eventually adopted Boulton's patented steam press design in 1810, standardizing national currency production and effectively dismantling domestic counterfeit networks.

According to the passage, which of the following explicitly accounts for the Soho Mint's ability to produce finished coin edges without requiring a secondary milling operation?