Friday Deep-Sea Picture (03/23/07)

Both Pictures from

 James Six (1731-1793) retired early from business to devote himself to the natural sciences. He is best known for the invention of the self-registering thermometer, first designed in 1780, which recorded the maximum and minimum temperatures reached. It was the most widely used thermometer for taking deep-sea temperatures until 1870. The thermometer’s susceptibility to pressure was addressed in 1869 by Dr W A Miller (1817-1870), then Vice-President of the Royal Society. Miller’s adaptation of Six’s design was made by the instrument maker L P Casella (1812-1897).

The bathythermograph is an instrument widely used to record the ocean temperature at various depths. It would be lowered from a moving vessel on a specially constructed cable and recorded the ocean temperature and the associated water pressure. Until the development of this thermometer, the thermocline (the layer of rapid temperature change between surface and deep water) had not been understood. The bathythermograph was able to show the structure of this layer more readily than could be achieved by measurements using a water bottle and thermometer. This instrument was made by S G Brown.

Dr. M (1801 Posts)

Craig McClain is the Executive Director of the Lousiana University Marine Consortium. He has conducted deep-sea research for 20 years and published over 50 papers in the area. He has participated in and led dozens of oceanographic expeditions taken him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses on how energy drives the biology of marine invertebrates from individuals to ecosystems, specifically, seeking to uncover how organisms are adapted to different levels of carbon availability, i.e. food, and how this determines the kinds and number of species in different parts of the oceans. Additionally, Craig is obsessed with the size of things. Sometimes this translated into actually scientific research. Craig’s research has been featured on National Public Radio, Discovery Channel, Fox News, National Geographic and ABC News. In addition to his scientific research, Craig also advocates the need for scientists to connect with the public and is the founder and chief editor of the acclaimed Deep-Sea News (, a popular ocean-themed blog that has won numerous awards. His writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web.

3 Replies to “Friday Deep-Sea Picture (03/23/07)”

  1. that looks just like the BT I used during SEA Semester (ah, the days of Niskin bottles and Secchi disks). Even then I remember it seeming so archaic-looking – something out of WWII. If I recall correctly, the temperature was recorded by etching a (gold coated?) glass slide inside. I assume newer, digital technology is available today?

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