Watson Glaser 5: Information

Example 3

Text
In 1839, the English scientist Charles Darwin received a detailed letter from the German geographer Alexander von Humboldt (in French) in which he compares many of his own observations about climate and species against those of Darwin. In the course of his life, Charles Darwin sent 6,500 letters and received 7,500. He corresponded with all the great European scholars of his day. However, like his contemporaries, Darwin worked largely alone and with his own money. His correspondence, now housed in a digital archive, shows how important exchange with others was for his ideas. Some letters, such as Humboldt's, were in fact a scientific article avant la lettre.

Interpretation
In the 19th century, French was the most common language for scientists to communicate with each other.

Answer
It is only stated that a letter was written in French, it cannot be inferred from this that this was common.