peristyle, &c., were lighted from above, and the cubicula and other small rooms generally derived their light from them, and not from windows looking into the street. The rooms only on the upper story seem to have been usually lighted by windows. The windows appear originally to have been merely openings in the wall, closed by means of shutters, which frequently had two leaves (_bifores fenestrae_). Windows were also sometimes covered by a kind of lattice or trellis work (_clathri_), and sometimes by net-work, to prevent serpents and other noxious reptiles from getting in. Afterwards, however, windows were made of a transparent stone, called _lapis specularis_ (mica); such windows were called _specularia_. Windows made of glass (_vitrum_) are first mentioned by Lactantius, who lived in the fourth century of the Christian era; but the discoveries at Pompeii prove that glass was used for windows under the early emperors.--(5.) The rooms were heated in winter in different ways; but the Romans had no stoves like ours. The cubicula, triclinia, and other rooms, which were intended for winter use, were built in that part of the house upon which the sun shone most; and in the mild climate of Italy this frequently enabled them to dispense with any artificial mode of warming the rooms. Rooms exposed to the sun in this way were sometimes called _heliocamini_. The rooms were sometimes heated by hot air, which was introduced by means of pipes from a furnace below, but more frequently by portable furnaces or braziers (_foculi_), in which coal or charcoal was burnt. The _caminus_ was also a kind of stove, in which wood appears to have been usually burnt, and probably only differed from the _foculus_ in being larger and fixed to one place. The rooms usually had no chimneys for carrying off the smoke, which escaped through the windows, doors, and openings in the roof; still chimneys do not appear to have been entirely unknown to the ancients, as some are said to have been found in the ruins of ancient buildings.