Billiard table 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..." A pool table, or pocket billiards table, has six – one at each corner of the table () and one at the midpoint of each of the longer sides ( or ). Pool tables come in different sizes, typically referred to as , , , or tables.
Billiard table the nap. , also known as (for their traditional shape), are inlaid at precise, evenly spaced positions along the rails of some tables (not usually on snooker tables) to aid in the aiming of bank or kick shots. There are seven along each long rail (with the side pocket interfering with where the seventh one would go, on pocket billiard tables) and three along each short rail, with each of the four corners counting as another in the mathematical systems that the diamonds are used to calculate. These sights divide the playing surface into equal squares. Books, even entire series