In 1784, Coleman purchased Speedwell Forge from his father-in-law. Although he no longer lived there, Coleman expanded the stone house around 1795, adding the east wing in the formal Georgian (or Federal) style popular at the time: two rooms deep, symmetrical, off a central hallway. The ceilings were higher and the moldings were much more intricate than the Colonial half. The stone privy appears to have been added around this time.
In the 1880s, steam radiators were added, the hardwood floors and windows were replaced, and corner cupboards were built in almost every room to match the original in the parlor. Electricity and indoor plumbing were added in 1941.
In the 1850s, anthracite coal was discovered in Eastern Pennsylvania, and ironmaking moved to Pittsburgh and then to Detroit. Speedwell Forge stopped production in 1854, and today there is nothing left.
The Speedwell property remained in the Coleman family, however, and they began breeding standardbred horses for sulky (or harness) racing. Their most famous stallion was Middletown, son of Hambletonian Ten. The circular driveway used to be a quarter-mile training track.
The Colemans sold the horses in 1898, and the property became a corn and dairy farm. In 1941, Margaret Coleman Buckingham sold the Speedwell property to Gerald and Kathryn Darlington. In the 1960s, the state of Pennsylvania purchased about 500 acres along Hammer Creek and dammed it, creating Speedwell Forge Lake. In the 1990s, Lancaster County purchased 300 acres and created the Speedwell Forge County Park. Both areas are ideal for hiking, kayaking, fishing, bird watching, and picnicking.