Final answer:
The author includes original reports of expeditions in order to provide historical context, offer firsthand accounts, and present scientific data.
Step-by-step explanation:
The author includes original reports of expeditions in the text to provide historical context, offer firsthand accounts, and present scientific data. By including these reports, the author can give readers a deeper understanding of the events and people being discussed. These firsthand accounts and scientific data help to establish the credibility of the information presented and make the subject matter more relatable and engaging for readers.