 When Russia renewed its earlier invitation to Humboldt, Humboldt accepted.The Russians sought to entice Humboldt by engaging his enduring interest in mining sites, for comparative scientific purposes for Humboldt, but for the Russians to gain expert knowledge about their resources.For Humboldt, the Russian monarch's promise to fund the trip was extremely important, since Humboldt's inherited 100,000 thaler fortune was gone and he lived on the Prussian government pension of 2,500–3,000 thalers as the monarch's chamberlain.