He was the literary editor for the Philadelphia Press in 1864.
Clapp discusses Mackenzie's affirmation in the Philadelphia Press that the poems published in "The Fire Fiend and other Poems, by Charles D. Gardette" appeared to be written by Poe. Clapp also notes Mackenzie's subsequent denials of Poe's authorship of the poems. Clapp tracks Mackenzie's responses to the poems: 30 Sept. 1864, "We believe that Poe wrote them," 17 Nov. 1864, "I thought Poe could not have written them," 21 Nov. 1864, "We never believed that Poe wrote them," and finally, "It did not decieve any critic in this country."
The piece ends with the "Query": What is the opinion of Dr. Mackenzie worth? Yours, without much doubt on the subject, A.B.
