Carom billiards
Professional straight rail in the United States was only seen for six years, from 1873 to 1879. It was followed by a game designed to reduce the use of the rail nurse so that spectators would not be bored by watching it. Today, straight rail play is not very common in the U.S. but it still popular in Europe, where it is thought to be a good practice game for balkline and three-cushion billiards. Europe hosts professional competitions, known as pentathlons after the ancient Greek Olympic competitions, in which straight rail is one of five billiards games at which players compete. The other four are called 47.1 balkline, cushion caroms, 71.2 balkline and three-cushion billiards.