Sounding is a historical nautical term for measuring depth. The term probably originated from the expression of sounding the well — the well being a shaftlike structure in old sailing vessels that reached all the way to the lowest part of the bilge. This shaft gave cargo free (uncluttered) access by the ships carpenter to the bilge spaces so that he might determine whether the ship was taking on water. That is, was the hull "sound", as in healthy. The term was also used for measuring dept… (More on Soundings)