John’s son, Jacob Weller (1752-1831) married ca. 1774 Anna Krall (1754-1812) daughter of Christian Krall. They were the parents of 9 children. Called "Old Jake" he was described as a teamster in family records. Jacob inherited or purchased from his brothers the tracts "Bucks Horn" and "Beauty". Jacob Weller died in 1831, leaving a will. At the time of his death Weller's Church on the land "Beauty" was still unfinished. His grave was the first in the United Brethren cemetery.

Jacob Weller, B.S. (1775-1846), . Was the eldest child of Jacob and Anna, born Jan 25th and baptized Feb 27th according to the records of Apples Church. His grandparents John and Catherine were sponsors. Jacob was a blacksmith and always signed documents "Jacob Weller, B.S." to distinguish himself from the several other local Jacob Wellers. In 1800 Jacob married Anna Margaret Weller, daughter of John Jacob (1739-1809) and grandaughter of tailor, John Jacob "The Moravian" who had emigrated in 1738 and owned extensive lands in the Jimtown area, some patented before Frederick county was formed.

This marriage united the two area Weller families, but it is unknown if they had some earlier Europeon family relationship. Jacob and Margaret had 5 children before her death in 1816; she is buried at Apples Church. In 1817 Jacob married Mary Love (1796-1872). By this union there were 10 more children.

Jacob B.S. began buying lots in the new "Town of Mechaniks" bordering his own lands. His first purchase on Aug, 1805 was for lots 6 & 7 on the north side of the Main Road. Construction on his large stone house began almost immediately; the date 1805' is inscribed on the west side chimney gable. This building was used as both a home and the first inn in town, with a large stable area on the east side. The Inn must have been quite successful since he received $4,000 for it at the time of its sale in 1813. The building has been little altered and is now restored as a significant example of Anglo-German architecture, listed as a Frederick Landmarks site and on the Inventory of Maryland Historic Sites.

Concurrent with his purchase on the north side of Main Street, Weller purchased 2 acres (lots 16,17,18 & 19) on the south side of the street. On this site he built a one and one half story stone building, probably with workshop behind it. This simple building would become known as the "Match House". From 1811 on, Jacob operated an edge tool factory making shovels, hoes, etc at a large tilt forge on Hunting Creek. After his marriage to Margaret Love he built an additional large brick home immediately west of the "Match House".

Jacob Weller, B.S. is credited with the manufacture of the first friction matches in the U.S., copied from French models imported to Frederick. The time was about 1825, for they were well known by 1832 when a student at Mount St. Mary's college wrote of buying some which sold for 12 and a half cents a block. Although requiring only simple ingredients, the experiments resulted in several explosions at the workshop. Jacob and son Joseph traveled extensively to sell the matches, with little success, especially when they attempted to sell the matches to area farmers, they were met with suspicion for their new-fangled and possibly dangerous product. Unfortunately Jacob failed to patent his invention; copy-cat manufacturers sprang up in the wake of his sales route. The first patent for friction matches was issued to a man in Massachusetts in 1836.

By the late 1830's Jacob was in financial ruin, forced to file as an Insolvent Debtor whose trustees sold off Jacob's lands., but despite his failures, Jacob remained a popular and respected citizen of Mechanicstown (renamed Thurmont in 1894).

Jacob was buried in the cemetery of the church he established. Weller's Church on the hill, was later called the United Brethren Church, but today, rechartered as Weller's United Methodist Church, it remains an enduring monument to Thurmont's pioneering industrialist and his family.