EH & Co. was founded in 1840 by Elias Howe Jr, made banjos in the last quarter of the 19th C in the Boston Mass., area. (He should not be confused with his cousin Elias Howe who was born in 1819 and invented the sewing machine.)
He started out as a student of the fiddle and in 1840 published a book of the tunes he had collected and this developed into a music publishing business, the rights to which he sold to Oliver Ditson in 1842. During the Civil war he made drums and fifes for the Massechusetts Regiment and no doubt his knowledge of drums spilled over into banjo making in the early 1880's.
The company bought out HC Barnes in 1898 and had numerous models in two ranges of banjos, their Academy (bottom end) and Superbo (top end)).
Images courtesty of the estate of Richard Evans