The Niskin bottle is a development of the Nansen bottle patented by Shale Niskin in March 1966. Instead of a metal bottle sealed at one end, the 'bottle' is a tube, usually plastic to minimize contamination of the sample, and open to the water at both ends. Each end is equipped with a cap which is either spring-loaded or tensioned by an elastic rope. The action of the messenger weight is to trip both caps shut and seal the tube.
A reversing thermometer may also be carried on a frame fixed to the Niskin bottle. Since there is no rotation of the bottle to fix the temperature measurement, the thermometer has a separate spring-loaded rotating mechanism of its own tripped by the messenger weight.
A modern variation of the Niskin bottle uses actuated valves that may be either preset to trip at a specific depth detected by a pressure switch, or remotely controlled to do so via an electrical signal sent from the surface. This arrangement conveniently allows for a large number of Niskin bottles to be mounted together in a circular frame termed a rosette. As many as 36 bottles may be mounted on a single rosette.
Thermistor temperature sensors are more commonly employed on Niskin bottle rosettes due to their higher accuracy compared to mercury thermometers.
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Famous quotes containing the word bottle:
“A baby nurse is one that changes diapers and loves ‘em dearly. Get up at all hours of the night to give ‘em the bottle and change their pants. If the baby coughs or cries, you have to find out the need. I had my own room usually, but I slept in the same room with the baby. I would take full charge. It was twenty-four hours. I used to have one day a week off and I’d go home and see my own two little ones.”
—Ruth Lindstrom (c. 1892–?)