大唐西域記 2.3: 3. Measures of Length.

2.3

To give a brief account of matters. In point of measurements, there is first of all the yôjana (yu-shen-na); this from the time of the holy kings of old has been regarded as a day's march for an army. The old accounts say it is equal to 40 li; according to the common reckoning in India it is 30 li, but in the sacred books (of Buddha) the yojana is only 16 li.
In the subdivision of distances, a yôjana is equal to eight krôśas (keu-lu-she); a krôśa is the distance that the lowing of a cow can be heard; a krôśa is divided into 500 bows (dhanus); a bow is divided into four cubits (hastas); a cubit is divided into 24 fingers (angulis); a finger is divided into seven barleycorns (yavas); and so on to a louse (yûkâ), a nit (likshâ), a dust grain, a cow's hair, a sheep's hair, a hare's down, copper-water, and so on for seven divisions, till we come to a small grain of dust; this is divided sevenfold till we come to an excessively small grain of dust (anu); this cannot be divided further without arriving at nothingness, and so it is called the infinitely small (paramdnu).