Although considerable remains of the Roman thermæ are still visible, yet, from the very ruinous state in which they are found, we are far from being able to arrive at the same accurate knowledge of their component parts and the usages to which they were applied, as has been done with respect to the balnea; or, indeed, to discover a satisfactory mode of reconciling their constructive details with the description left us by Vitruvious and Lucian. All, indeed, is doubt and guesswork. Each of the learned men who have pretended to give an account of their contents differing in all the essential particulars from one another; and yet the general similarity of the ground plan of the three which still remain cannot fail to strike even a superficial observer; so great indeed that it is impossible not to perceive at once that they were all constructed upon a similar plan. Not, however, to discuss the subject without enabling the reader to form something like a general idea of these enormous edifices, which from their extent and magnificence have been likened to provinces, a ground plan of the thermæ of Caracalla is annexed, which are the best preserved among those remaining, and which were perhaps more splendid than all the rest. Those apartments of which the use is ascertained with the appearances of probability, will be alone marked and explained. The dark parts represent the remains still visible; the open lines are restorations. [Illustration: Hypocaust for Heating Water, Thermæ of Caracalla From an old woodcut] A is a portico fronting the street made by Caracalla when he constructed his thermæ. B are separate bathing-rooms, either for the use of the common people, or perhaps for any person who did not wish to bathe in public. C are apodyteria attached to them. D, D and E, E, the porticos. F, F, exedra in which there were seats for the philosophers to hold their conversations. G, passages open to the air. H, H, sladra. I, I, possibly schools or academies where public lectures were delivered. J, J and K, K, rooms appropriated to the servants of the bath. In the latter are staircases for ascending to the principal reservoir. L, space occupied by walks and shrubberies. M, the arena or stadium in which the youth performed their exercises, with seats for spectators. N, N, reservoirs with upper stories; O, aqueduct which supplied the baths. P, cistern. This external range of buildings occupies one mile in circuit. We now come to the arrangement of the interior, for which it is very difficult to assign satisfactory destinations. Q represents the principal entrances, of which there were eight. R is the natiatio or cold water baths to which the direct entrance from the portico is by a vestibule on either side marked S, and which is surrounded by a set of chambers that serve most probably as rooms for undressing and anointing.