William Lawson King and his family moved here in 1925, and for more than 60 years the property formed part of their dairy operation, the largest in the county, with 450 registered Holstein cows. More than 100 cows were milked here twice daily, 365 days a year, and the remaining farm buildings illustrate this 20th-century industry in and around the City of Rockville. The hay drying shed was a simple pole barn with a gas furnace enclosed at one end, used in hay production to prepare an important winter source of protein for the dairy cows. Fresh hay was loaded onto wagons in the fields and brought to the shed, where channels in the floor guided the wagon wheels beneath ceiling hatches fitted with canvas covers that dropped over the hay loads. Ten wagons could be processed at one time as a blower sent hot air from the gas-fired furnace into the attic and through the hatches to dry the hay. This machinery reduced drying time, helped farmers cope with surprise rains during harvest, and was especially important in preventing hay fires caused by excessive moisture, which encouraged bacterial growth that generated heat and could ignite stored hay within six weeks. Farmers aimed for a low moisture content of 25 percent before winter storage, and at the King Farm hay was stored in several buildings, including lofts above the two large dairy barns.