Master carpenter James Dinsmore oversaw construction of the Ice House to Jefferson's design in 1802. Enslaved and hired workers filled it each year between November and February with ice cut from the nearby Rivanna River, shallow ponds, or snow collected from mountaintop. The ice usually lasted through the summer and was mainly used to preserve meat and butter and to chill wine, while snow was used to make ice cream. The circular Ice House, 16 feet across and 16 feet deep, was intentionally located on the colder, north side of the house to help preserve the ice, and the North Terrace above offered further protection from sun and water. The access door was locked for safety and to prevent theft. When winter weather yielded ice at least an inch thick, Jefferson's overseer assembled carts and wagons with teams and drivers, many hired locally, to transport the ice to the mountaintop. When it was filled for the first time, Jefferson recorded that it had taken 62 wagon loads of ice at a cost of $70 for labour, feeding, drink, and other expenses. The ice was packed solid and insulated around the perimeter with straw or wood shavings. As the ice melted each week, water had to be drawn off by bucket, by a pump, or by a hand-drawn bucket, rather than the pulley system Jefferson first envisioned. Its contents also once helped save the main part of the house from fire, when snow from it was used in May 1819 to cover the adjacent terrace and keep a blaze at the North Pavilion from spreading.