wah [Thai. วๅ]

In Thailand, ? – 20^th century, a unit of length, the fundamental unit in Thailand's system of units of length. Since the standardization of 1923 = 2 meters (about 78.74 inches)¹. Also romanized as wa, voua, vöuá and vouah.

Between the latter half of the 19th century and 1923, the wah was 80 inches (2.032 meters). The prototype was a silver bar bearing two scratches, the distance between them being 1 wah. In 1876, this prototype was examined by the Standards Department of the British Board of Trade and the distance determined to be 79.999 inches.² Interestingly, Siamese law specified that the temperature at which prototypes represented their unit was 85° Fahrenheit, a sensible choice for a tropical country.

Before the 80-inch definition, the wah was about 1.922 meters.

1. United Nations, 1966.

2. W. A. Browne, 1879.