Around 1747 an individual with connections to both the Dunkards and the Ephrata Cloister built a stone house on land previously owned by Dunkards. The structure, used for church retreats, still stands today, and is known as "The Monastery", a remaining witness to the Wissahickon's days as an isolated religious refuge. The same steep slopes and gorge that provided an attractive isolation to religious adherents in the 17th and early 18th centuries provided an efficient source of energy for the development of water mills in later years. One miller had by 1690 already constructed a dam, sawmill, gristmill, and house by the narrow shelf of land at the confluence of the Wissahickon with the Schuylkill River, but the rugged terrain of the valley forestalled further development alongside the stream itself. By 1730, however, eight mills had been constructed, and by 1793, twenty-four, along with many dams. Most of America was still wilderness, but the Wissahickon Valley was a developing industrial center. There were more than fifty watermills by 1850, though the thickly forested region about the stream still retained the character of a wilderness. Access roads were being constructed into the steep valley, but there was still no road that followed the stream itself. The nature of the rugged terrain can be comprehended in an event that had occurred during the Revolutionary War Battle of Germantown, which was fought not too far from the stream. The American General John Armstrong, compelled by the rough terrain to abandon a cannon in the valley, expressed his contempt for the "horrendous hills of the Wissahickon." Later legends tell of American spies taking advantage of the terrain to retrieve information from an informant named "Mom Rinker", who allegedly perched atop a rock overlooking the valley to drop balls of yarn which contained messages about British troop movements during the occupation of Philadelphia. This is likely a legend, for other stories speak of a witch named "Mom Rinkle" who had little to do with the Revolution. There is a Mom Rinker's Rock in the park today. Not until 1826 were the cliffs near the creek's mouth blasted away to provide access to the cluster of mills at Rittenhousetown, approximately 1.5 mi (2.4 km) up the creek on Paper Mill Run (also known as Monoshone Creek), a small tributary of the Wissahickon. Here William Rittenhouse (grandfather of the astronomer David Rittenhouse) had in the early 18th century built the first paper mill in America.