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.
Selama periode ini, meski telah kehilangan hampir semua catatan dari ekspedisinya di Amerika Selatan, ia menulis enam makalah akademik (termasuk "On the Monkeys of the Amazon") dan dua buku yang berjudul Palm Trees of the Amazon and Their Uses dan Travels on the Amazon.