Darwin's father gave him an allowance that enabled him to put aside other careers. As a scientific celebrity with a reputation established by his fossils and Henslow's publication of his letters on South American geology, Darwin toured London's social institutions. By this time, he was part of the "scientific establishment", collaborating with expert naturalists to describe his specimens and working on ideas he had been developing during the voyage. Charles Lyell gave him enthusiastic backing. In December 1836, Darwin presented a talk to the Cambridge Philosophical Society. He wrote a paper proving that Chile, and the South American continent, was slowly rising, which he read to the Geological Society of London on 4 January 1837.