This British trip, sponsored by the Royal Society, was to discover magnetic and geographic features of the Antarctic. The expedition was prepared with great care by James Clark Ross, already familiar with Polar navigation. The two ships left the United Kingdom on 19 September 1839, stopping to explore the Kerguelen Islands in 1840, and then on Tasmania to build a magnetic observatory for the Antarctic and to conduct cartographic work. Mount Erebus and the Ross Sea were discovered during this journey. After three attempts, Ross admitted that the magnetic pole lay in land that he could not reach. Following the footsteps of his uncle John Ross, he performed the first deep sea surveys up to 4800 m (2677 fathoms), using ropes. Unfortunately biological specimens collected decomposed.