Letter to William H. Channing
p201“His book, also, is in press.”
Fuller, Margaret. The Letters of Margaret Fuller. Edited by Robert N. Hudspeth. Vol. II. Ithaca: Cornell University Press, 1984.
Inferred Hudspeth identified 'His book' as Emerson's Essays: First Series, sent to publisher on 1 January 1841 and published by James Munroe on 20 March 1841.