But we must not speak harshly of the ancients because they were slow in improving their methods of heating for in truth the modern world has not done as well in this direction as might have been expected. In a book of travels written only sixty years ago may be found the following passage: "In Normandy, where the cold is severe and fire expensive, the lace-makers, to keep themselves warm and to save fuel, agree with some farmer who has cows in winter quarters to be allowed to carry on their work in the society of the cattle. The cows would be tethered in a long row on one side of the apartment, and the lace-makers sit on the ground on the other side with their feet buried in the straw." Thus the lace-makers kept themselves warm by the heat which came from the bodies of the cattle; the cows, in other words, served as stoves. This barbarous method of heating, was practised in some parts of France less than sixty years ago. [Illustration: FIG. 3.--A ROMAN BRAZIER.] The ancient peoples around the Mediterranean may be excused for not making great progress in the art of heating, for their climate was so mild that they seldom had use for fire in the house. Nevertheless there was in use among these people an invention which has in the course of centuries developed into the stove of to-day. This was the _brazier_, or warming-pan (Fig. 3). The brazier was filled with burning charcoal and was carried from room to room as it was needed. The unpleasant gases which escaped from the charcoal were made less offensive, but not less unhealthy, by burning perfumes with the fuel. The brazier has never been entirely laid aside. It is still used in Spain and in other warm countries where the necessity for fire is rarely felt. The brazier satisfied the wants of Greece, but the colder climate of Rome required something better; and in their efforts to invent something better, the ancient Romans made real progress in the art of warming their houses. They built a fire-room--called a _hypocaust_--in the cellar, and, by means of pipes made of baked clay, they connected the hypocaust with different parts of the house (Fig. 4). Heat and smoke passed up together through these pipes. The poor ancients, it seems, were forever persecuted by smoke. However, after the wood in the hypocaust was once well charred, the smoke was not so troublesome. The celebrated baths (club-rooms) of ancient Rome were heated by means of hypocausts with excellent results. Indeed, the hypocaust had many of the features and many of the merits of our modern furnace. Its weak feature was that it had no separate pipe to carry away the smoke. But as there were no chimneys yet in the world, it is no wonder there was no such pipe. [Illustration: FIG. 4.--A ROMAN HYPOCAUST.]