Was pond ice used as the first refrigerator?

In a way, yes. Before the invention of refrigeration machines in 1805, people cut ice from ponds in winter and stored it in an icehouse. These icehouses were pits dug into the ground and lined with wood or straw and packed with snow and ice. They were covered with an insulated roof. Because cold air sinks, the pit remained very cold, keeping foodstuffs cold and unspoiled until the early summer months.