[citation needed] By the late 1830s, Agate was exhibiting his work at the National Academy of Design in New York, and had established himself as a skilled painter in oils.

For much of his landscapes,[citation needed] Agate used a camera lucida, a device which projected the scene onto a piece of paper for purposes of tracing.

[2] During the visit of the expedition to the Ellice Islands (now known as Tuvalu) Alfred Thomas Agate recorded the dress and tattoo patterns of men of Nukufetau.

Agate lived in Washington, D.C., from 1842 onward, but his health suffered severely from the expedition and he died four years later of consumption.

Botanist Asa Gray used Agate's drawings and the expedition's specimens for botanical reports, and named a violet, Agatea violaris, after him.