To (a unit of volume in old Japanese system of weight and measures) (斗)

To (斗; a unit of volume)
To is a unit of volume in the East Asian system of weights and measures.

To is the name of the 11th string of so (a long Japanese zither with 13 strings).

In this section, the former is explained.

10 sho is equalized with 1 to, and 10 to is equalized with 1 koku (sho and koku are also the units of volume). In Japan, 1 sho was set at 1.8039 liters in the Meiji period, so 1 to became 18.039 liters.

In China, 1 sho was set at 1 liter, so 1 to (dou in pinyin) became 10 liters. However, the volume of to differs from time to time, and it tends to become larger as the time comes closer to today. 1 to was set at 1.94 liters in the age of the Zhou Dynasty, and it was at 3.43 liters in the Qin Dynasty. In the age of the Later Han Dynasty, 1 to was reduced to 1.98 liters, but after that, the size continued to grow as 1 to was set at 2.02 liters in the age of the Wei and West Jin Dynasties, 5.94 liters in the age of the Sui and Tang Dynasties, and was set at 10.74 liters, which was almost the same size as present, in the age of the Ming Dynasty.

In Japan, the cuboid tin can of about 1 to volume was once called 'Ittokan' (can of 1 to). After World War II, it was widely called as 'go-gallon kan' (can of 5 gallons), and later, it was formally renamed into 'Juhachi-liter kan' (can of 18 liters). The plastic tank for storing kerosene and other liquid (commonly called poli-tank [polystyrene tank]) was made as a replacement for Ittokan, of which volume is 1 to (18 liters) or a bit larger, 20 liters.