The first consignment of dressed beef to leave the Chicago stockyards was in 1857, and was carried in ordinary boxcars retrofitted with bins filled with ice. Placing the meat directly against ice resulted in discoloration and affected the taste, hence proved impractical. During the same period Swift experimented by moving cut meat using a string of ten boxcars which ran with their doors removed, and made a few test shipments to New York City during the winter months over the Grand Trunk Railway (GTR). The method proved too limited to be practical. Detroit's William Davis patented a refrigerator car that employed metal racks to suspend the carcasses above a frozen mixture of ice and salt. He sold the design in 1868 to George H. Hammond, a Detroit meat-packer, who built a set of cars to transport his products to Boston using ice from the Great Lakes for cooling. The loads had the unfortunate tendency of swinging to one side when the car entered a curve at high speed, and the use of the units was discontinued after several derailments. In 1878 Swift hired engineer Andrew Chase to design a ventilated car that was well-insulated, and positioned the ice in a compartment at the top of the car, allowing the chilled air to flow naturally downward.