was drawn off from the lowest boiler a
supply of tepid water flowed down from the boiler next above, and from
the highest to the middle boiler.

A smaller suite of bathing apartments adjoining the men's establishment
was for the use of women.

The most important baths formed only a part of the great establishments
called _thermae_. Adjoining the baths of the thermae were a gymnasium for
sports and exercises, a library for the studious, lounging places for
the idle, halls for poets and philosophers, in which they declaimed and
lectured, museums of art, and sometimes shady groves. These complete
establishments were first erected by Marcus Agrippa in the time of
Augustus. Succeeding emperors vied with each other in providing
magnificent thermae, and the ruins of the Baths of Caracalla remain in a
wonderful state of preservation to this day. The building of these baths
began in A.D. 216. The structure, 1,050 ft. long and 1,390 ft. broad,
was on a scale of almost incredible magnificence. Priceless statues and
rare objects of art have been unearthed from the ruins. In recent years
excavations have revealed a complicated system of subterranean corridors
and galleries which existed for the purpose of carrying leaden
water-pipes to the baths, and providing a passage-way for the host of
slaves who acted as bath-attendants. The great buildings were well lit
by windows in the walls of the courtyards, and these openings also
allowed for ventilation. A great stadium and beautiful gardens adjoined
the Baths of Caracalla. In the north-west section of these baths Alessio
Valle has very recently discovered the remains of a great public
library. When Caracalla pillaged Alexandria he probably carried off many
of the books from the famous library there to enrich his baths. The
ruins of the library in the Baths of Caracalla reveal circular tiers of
galleries for the display of manuscripts and papyri. There were 500
rooms round these baths. The great hall had a ceiling made in one span,
and the roof was an early example of reinforced concrete, for it was
made of concrete in which bronze bars were laid. The lead for the
water-pipes was probably brought from Cornwall.

The Thermae of Diocletian could accommodate 3,200 bathers. Its tepidarium
was 300 ft. long by nearly 100 ft. wide, "vaulted in three bays with
simple quadripartite groining, which springs from eight monolithic
columns of Egyptian granite about 50 ft. high and 5 ft. in diameter