After his return to the UK, Wallace spent 18 months in London living on the insurance payment for his lost collection and selling a few specimens that had been shipped back to Britain prior to his starting his exploration of the Rio Negro until the Indian town of Jativa on Orinoco River basin and as far west as Micúru (Mitú) on the Vaupés River. He was deeply impressed by the grandeur of the virgin forest, by the variety and beauty of the butterflies and birds, and by his first encounter with Indians on the Vaupés River area, an experience he never forgot. During this period, despite having lost almost all of the notes from his South American expedition, he wrote six academic papers (which included "On the Monkeys of the Amazon") and two books; "Palm Trees of the Amazon and Their Uses" and "Travels on the Amazon". He also made connections with a number of other British naturalists.