# Gnomon: Chinese Dominoes

It appears that European dominoes came to Europe from China some time in the 18th century.

Chinese dominoes are similar to European dominoes, but have subtle differences.

While European dominoes are the shape of 2 squares stuck together, making them 2 x 1, Chinese dominoes are longer and thinner. I don't know the exact ratio, but it looks like 2.5 x 1. They don't have a line marked across the centre separating the two halves.

European dominoes can be black or white. The name "bones" is sometimes used for the pieces and the pool of unused pieces is called the "boneyard", suggesting they were originally all white. White ones usually have black spots. Black ones can have white spots or coloured spots, with all the 1's of one colour, all the 2's of another and so on.

The Chinese dominoes I've seen are black, but the Cantonese name 'gwat pai' means 'bone tiles' so they may also come in white. The spots on a black domino are coloured red or white:

• 1 and 4 are coloured red
• 2, 3, 5 and 6 are coloured white
• the 'double 6' tile has a special colouring:

WWW RRR

RRR WWW

In European dominoes each of the two squares may be blank or a number from 1 to 6. Every possible combination occurs once only, so there are 28 pieces.

Chinese dominoes do not include blanks. The pieces can have a number from 1 to 6 at either end. This gives 21 unique pieces. A set of Chinese dominoes includes duplicates of 11 of the pieces, making 32 pieces in a set.

The following pieces occur once each in a set:

36, 45, 35, 26, 34, 25, 24, 14, 23, 12

The following pieces occur twice each in a set:

66, 11, 44, 13, 55, 33, 22, 56, 46, 16, 15

The 3-3 piece is exceptional in that may be styled with two dots along the central line dividing the two halves of the domino, and the other four dots evenly spaced along the central axis.

The game of Chinese dominoes divides the pieces into those of which there is only one example, which are called 'Military', and pieces which have two examples, which are called 'Civil'.

Each of the pieces in the game has a special name in Chinese.