What kinds of measurements did the Challenger Expedition make during its voyage?

The Challenger Expedition (1872–1876) was a landmark voyage that provided the first systematic exploration of the world's oceans. During its journey, the expedition conducted observations at 362 stations, performing 492 deep-sea soundings and 133 dredgings to gather data.1

The measurements and investigations made by the crew included:

• Oceanic Physical Properties: Scientists determined ocean temperatures and studied ocean currents. They also made significant observations regarding the constancy of major constituents in seawater, which helped establish methods for mapping water density.12
• Bathymetry: The expedition determined the depths and contours of the great ocean basins using wire-line soundings, leading to the discovery of the Mid-Atlantic Ridge.13
• Biological and Geological Sampling: Dredges were used to collect samples of rocks and sediments from the seafloor. Additionally, the expedition carried out extensive biological investigations, collecting vast numbers of plants and animals and recognizing the importance of plankton as a food source for marine life.314
• Charting and Surveying: The crew engaged in general charting and surveying of the marine environment, contributing to the foundations of modern oceanography and marine biology.14