Heated plant houses

2049. The first mode of heating plant-houses was by furnaces; and we find Solomon de Caus heated his temporary orange house by four furnaces all the winter. The green-house at Chelsea was heated by an open charcoal fire in the floor, and that of Evelyn by a closed furnace or oven. The next step appears to have been carrying the chimney of the furnace under the floor of the greenhouse, and thus forming what was called a smoke flue; and various modifications of this ended in the hot-air flues of modern times.