NANSEN BOTTLE

ocean-water sampler devised late in the 19th century by the Norwegian oceanographer Fridtjof Nansen and subsequently modified by various workers. The standard Nansen bottle has a capacity of 1.25 litres and is equipped with plug valves at either end. The bottle is affixed to a winch wire with its valves open, and the winch wire is paid out until the bottle is approximately at its desired sampling depth. A weight, or messenger, is then allowed to slide down the cable. The upper attachment of the Nansen bottle is disengaged from the cable by the impact of the messenger; and the bottle is reversed end over end, its valves closing in the process to trap the water sample. Thermometers usually are attached to the Nansen bottle to record the temperature and pressure of the sample site. Several Nansen bottles are employed during a single hydrographic cast, each bottle releasing another messenger when tripped, in order to trigger the deeper bottles in turn.