Convert from cana (canna, canne) to barleycorn

Unit Definition (cana (canna, canne))
The caña (canna, canne) are traditional units of distance in Spain, Italy, and southern France, respectively. The caña varied in size, but it was most often defined as 8 palmos, which makes it the Mediterranean version of the fathom, equal to roughly 2 meters or 6.5 feet. In Italy a measuring stick is still called a canna metrica. The unit is sometimes translated to "rod" in English, but "fathom" is the proper choice.

Unit Definition (barleycorn)
The Barleycorn is an old English unit of length. The custom of using seeds as units of length or weight is very common in farming societies. In Anglo-Saxon England, where barley was a basic crop, barleycorns played this traditional role. The weight of a barleycorn, later renamed the grain, is the original basis of all English weight systems including the older troy system and the later avoirdupois system. As a length unit, 3 barleycorns were equal to the Saxon ynce (inch). The English foot was actually defined as 12 of these ynces, that is, as 36 barleycorns.