Seymour completed five panels in 1795 for the American edition of the
Encyclopædia Britannica printed by
Thomas Dobson. He established himself in Philadelphia by 1796, where he was an engraver and painter through 1822. He was a colleague of
Thomas Sully and made engravings of
William Birch's work in 1801, 1803, and 1804. His engraving of Thomas Birch's
Philadelphia, taken from Kensington drawing of 1811 is among the collection of the
Philadelphia Museum of Art. His works were exhibited at the
Pennsylvania Academy of the Fine Arts shows, and
Man directing woman into a cave, an engraving of
John James Barralet's work, and other illustrations. Most of the works that he exhibited at the Academy were
plein air landscapes and yet he mainly focused his energy on his commercial engraving business. Either directly or through his connections, Seymour was familiar with the nation's leading artistic and scientific organizations: the
Academy of Natural Sciences of Philadelphia,
Philadelphia Museum of Art, and
American Philosophical Society. Seymour was an associate member of the Society of Artists. He became increasingly interested in landscape paintings and traveled to the countryside with Sully and along the
Schuylkill River with Jarvis and Birch to make sketches. These organizations helped define the objective for
Stephen Harriman Long's scientific expeditions. ==Long expeditions==