Illustrated Companion to the Latin Dictionary/Sphaeristerium

This article incorporates text from a publication now in the public domain: Rich, Anthony (1849). The illustrated companion to the Latin dictionary, and Greek lexicon. p. vi. OCLC 894670115. https://archive.org/details/illustratedcompa00rich. 

SPHAERISTE'RIUM (σφαιριστήριον). An apartment for playing the game at ball, attached to the Gymnasia, Thermae, and other places of public resort, as well as to the private mansions of wealthy people; and as the players at this game were usually stripped, it was frequently warmed by flues from a furnace (hypocausis) underneath the floor. Plin. Ep. ii. 17. 12. Id. v. 6. 27. Suet. Vesp. 20. Lamprid. Alex. Sev. 30.