Maximilian recorded in his journal that on August 7, during an outing along the Lehigh River, several bullfrogs were captured and that "Mr. Bodmer made a sketch of two of them." He explained that such lively specimens were tied down with strings to hold them in position while Bodmer executed his careful studies.

On the afternoon of July 27, Maximilian called upon Dr. Saynisch to inspect his collection of scientific books and related natural history specimens, for the most part locally obtained. Later, accompanied by Bodmer, they took a stroll along the Lehigh River past Moncasa Creek. Bodmer's softly washed watercolor of the scenery along the Lehigh appears to have been scrubbed in spots and remains in an unfinished state.

Moncasa Creek, a tributary of the Lehigh River, separated Lehigh and Northampton counties and divided the town of Bethlehem itself. Bodmer's pencil sketch of the bridge over the Moncasa at Bethlehem was made on or before July 28.