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Before mechanical refrigeration existed, the ice trade supplied entire cities with blocks cut from frozen lakes and ponds each winter. Workers used horse-drawn saws to score the ice into uniform blocks, which were then hauled by sled into insulated icehouses packed with sawdust to slow melting through the summer months. By the mid-1800s, entrepreneurs were shipping New England ice by sailing vessel to ports as distant as Calcutta, wrapping the cargo in sawdust and straw to reduce loss during the months-long voyage. Although a significant fraction of each shipment still melted before arrival, the trade remained profitable because tropical buyers, who had no local means of producing ice, were willing to pay prices far above the harvesting cost.