Walter McCool rebuilt the 35'X 50' 2.5 stone grist mill in about 1800. The mill was formerly known as Weaver Mill and later as Detwiler Mill in the village of California, Pa.

The earlier grist mill and saw mill was built by Walter McCool c. 1750. The mill was operated by the Weaver family for the majority of the 1800's.

Steam powered from 1876 forward, S. Detwiler operated the mill a little beyond 1914. The headrace runs alongside Cherry Road after it comes off the Tohickon Creek. The mill pond is across Cherry Road west of Gross Road.

The mill also has a stone basement, if not a complete lower story. The mill has been a residence since at least the late 1970's.