On this day in history,...

...in 1894, when Norwegian oceanographer Fridtjof Nansen introduced his revolutionary water-sampling device—the Nansen bottle began its journey as the standard instrument for collecting seawater samples at depth. This marked a crucial step in the development of observational oceanography, enabling systematic studies of the vertical structure of the ocean.

The Nansen bottle was a brass or metal cylinder designed to be deployed on a cable in series, at various depths. Once it reached the desired depth, a messenger weight was sent down the wire to trigger the inversion mechanism of the bottle, sealing both ends and trapping a sample of seawater. Simultaneously, the inversion would flip a pair of protected reversing thermometers, designed to record the in situ temperature at the moment of closure.

This innovation allowed oceanographers for the first time to obtain discrete samples of water and temperature measurements at known depths across the global ocean, forming the backbone of hydrographic surveys for much of the 20th century. However, despite its utility, the Nansen bottle had limitations—particularly its reliance on moving parts, fragile glass thermometers, and the need for inversion.

In 1966, American oceanographer Shale Niskin introduced a modern alternative: the Niskin bottle. Unlike its predecessor, the Niskin bottle did not require inversion, used spring-loaded end caps, and could be made of non-metallic materials, reducing contamination risks in chemical sampling. Multiple Niskin bottles could be mounted in a rosette frame and combined with CTD profilers, allowing simultaneous collection of water samples and high-resolution physical data. This integration has since become standard in modern oceanography.

The legacy of the Nansen bottle lives on in the design philosophy of the Niskin, which remains the dominant water sampler in research today. Together, they represent a lineage of ingenuity that has shaped how we observe, sample, and understand the ocean’s interior.

Note: June 1 is an approximate date chosen to commemorate the introduction of the Nansen bottle in 1894, as no exact day is documented.

Sources

•    Nansen, F. (1902). The Oceanography of the North Polar Basin. Scientific Results of the Fram Expedition.
•    Sverdrup, H. U., Johnson, M. W., & Fleming, R. H. (1942). The Oceans: Their Physics, Chemistry, and General Biology. Prentice-Hall.