<P> The slate bed of a carom billiard table must have a minimum thickness of 45 millimeters and is often heated to about 5 degrees C (9 deg 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 especially important requirement for the games of three - cushion billiards and artistic billiards . </P> <P> Heating table beds is an old practice . Queen Victoria had a billiard table that was heated using zinc tubes, although the aim at that time was chiefly to keep the then - used ivory balls from warping . The first use of electric heating was for an 18.2 balkline tournament held in December 1927 between 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 ..." </P> <P> A pool table, or pocket billiards table, has six pockets--one at each corner of the table (corner pockets) and one at the midpoint of each of the longer sides (side pockets or middle pockets). </P> <P> Pool tables come in different sizes, typically referred to as 9 - foot (2.7 m), 8.5 ft (2.6 m), 8 ft (2.4 m), or 7 ft (2.1 m) tables . In all cases, the table is rectangular with a 2: 1 ratio (e.g. 9 × 4.5 ft). </P>

What size is an 8 ball pool table