Underneath the cloth of billiard tables is a very hard rock called slate. The slate bed of a billiard table is often heated to about 5 °C/9 °F above room temperature, which helps to keep moisture out of the cloth to aid the balls rolling and rebounding in a consistent manner, and generally makes a table play faster. A heated table is required under international carom rules and is an important requirement for the games of three-cushion billiards and artistic billiards. Heating table beds is an old practice. Queen Victoria of England (1819–1901) had a billiard table that was heated using zinc tubes, At that time, though, the reason for the heating was different. The heat was used to keep ivory balls from going out of shape (warping). The first use of electric heating was for a tournament in the game of "18.2 balkline", that was held in December 1927 between two players: Welker Cochran and Jacob Schaefer, Jr. "The New York Times" announced it with fanfare: "For the first time in the history of world's championship balkline billiards a heated table will be used ..."