Figure 12. E. B. Helland-Hansen’s photometer. Left: device before opening. Middle: Device during exposure. Right: Device after closing. Invented by Bjorn Helland-Hansen in 1910, this photometer was used aboard the MICHAEL SARS in the North Atlantic. It was first used near the Azores at depths of 500 to 700 meters.
Photo Category: Oceanography - Historical instruments