From the tepidarium, a door which closed by its own weight, to prevent the admission of cold air, opened into No. 13, the thermal chamber. After having gone through the regular course of perspiration, the Romans made use of instruments called strigils, to scrape off the perspiration, much in the same way as we are accustomed to scrape the sweat off a horse with a piece of iron hoop after he has run a heat or come in from violent exercise. These instruments, many of which have been discovered among the ruins of the various baths of antiquity, were made of bone, bronze, iron and silver. The poorer classes were obliged to scrape themselves, but the more wealthy took their slaves to the baths for the purpose, a fact which is elucidated by a curious story related by Spartianus. The Emperor while bathing one day, observing an old soldier, whom he had formerly known among the legions, rubbing his back as the cattle do against the marble walls of the chamber, asked him why he converted the walls into a strigil, and learning that he was too poor to keep a slave he gave him one, and money for his maintenance. On the following day, upon his return to the bath, he found a whole row of old men rubbing themselves in the same manner against the wall, in the hope of experiencing the same good fortune from the prince's liberality; but instead of taking the hint, he had them all called up and told them to scrub one another. [Illustration: Coppers for Heating Water. From an old woodcut] The strigil was by no means a blunt instrument, consequently its edge was softened by the application of oil which was dropped on it from a small vessel. This vessel had a narrow neck, so as to discharge its contents drop by drop. Augustus is related to have suffered from an over violent use of this instrument. Invalids and persons of delicate habit made use of sponges, which Pliny says answered for towels as well as strigils. They were finally dried with towels and anointed. The common people were supplied with these necessaries in the baths, but the more wealthy carried their own with them.