Early attempts by François Péron and Louis Depuch to measure the temperature at various depths in the ocean, and their thoughts about a hot versus a cold interior of the Earth

During the course of a voyage of discovery to Australia the zoologist François Péron, aided in its early stages by the geologist Louis Depuch, took regular measurements of air and water temperatures at the surface of the sea and, on four occasions, at various depths in the equatorial parts of the Atlantic Ocean. The data they collected made a useful contribution to a better understanding of the oceanic environment. A comparison of their findings with results obtained on the voyages of Captain Phipps to northern latitudes and by scientists on Captain Cook's second voyage in waters of the South Pacific Ocean, enabled Péron to declare that temperatures in the world's oceans, at all latitudes, decreased with depth. Considering the implication of this trend to ideas on the temperature in the interior of the Earth, Depuch sided with scholars who believed that its centre was hot, while Péron, relying on his own observations and those of other investigators, tended to favour the cold Earth theory, but was hesitant in reaching a firm conclusion.