Edward was developing his interest in geology, which had been awakened by talks in Amherst by Amos Eaton while on a lecture tour. In the summer of 1817, he sent mineral samples to Benjamin Silliman, who was at that time establishing the science curriculum at Yale College in New Haven, Connecticut. Encouraged by Silliman’s courteous reply, Edward sent more samples in October, accompanied by a geological map he had made of a section of the Connecticut River Valley. It must have been quite a surprise for Silliman to see such accomplished work coming from this unknown young man. In his letter, Edward introduced Orra as his “assistant” and mentioned her talents as a botanical illustrator and landscape artist.
Silliman was in the process of founding the American Journal of Science, which went on to become the premiere scientific publication in the country for many years. He was impressed with Edward's work and delighted to publish it. However, when he gently turned down as insufficiently scientific a landscape by Orra that Edward hoped to include, Edward, in flustered embarrassment, claimed never to have thought seriously that the drawing would be accepted. He quickly made up for any hint of insult to Orra. The drawing was published instead in Port Folio, a Philadelphia literary magazine, with Edward's description of the view a few pages later. A glowing review of Jacob Bigelow's American Medical Botany appeared in an issue of Port Folio earlier that year, with high praise for the drawings. The review does not single out any drawings identified as Orra's, but it may have been a useful connection.
His relationship with Silliman became most important in Edward's life. After a few months of study in 1818, Silliman awarded Hitchcock an honorary master's degree from Yale. He was a mentor who graciously moved into the role of colleague as Edward's star rose, and a staunch defender when Edward's scientific ideas were ridiculed. They sent greetings to each other's wives in their professional correspondence and occasionally stayed in one another's home (usually Edward at Silliman's) when they needed to meet in person. Their similarity in religious belief further cemented what was for both of them an important professional relationship that, with only one lamentable break, lasted the rest of their lives.