Microscopic view of 'mud' from Challenger Report, Narrative Vol.I pt 2 plate 0 figure 12; section of palagomitic lapilli. HMS Challenger made a three and a half year circumnavigation from December 1872 to May 1876. The voyage is particularly famous since it is said to mark the beginning of modern oceanography. The ship was adapted to accomodate the scientists' measurement of physical data and the collection of samples from the ocean and sea floor.
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