[Offprint, inscribed to Mary Proctor, containing autograph note.] Detection of Venus' Rotation Period and of the Fundamental Physical Features of the Planet's Surface.

5pp., 8vo, with five plates. Stitched. In brown printed wraps headed 'Compliments of the Author', with 'Reprint from Popular Astronomy' at foot. Heavily aged, in worn and stained wraps repaired with tape. At the head of the cover Lowell has written 'iss Mary E. Proctor'. Manuscript note in another hand (presumably Procter's) on cover: 'Contains a note in Lowell's own handwriting on page 2'. Lowell's autograph note on p.2, with slight loss due to trimming of the edges of the pamphlet, reads: 'For further story by me see Jan. '97 pular stronomy'. There are further notes, in pencil in another hand (presumably Procter's), in the margin of p.4. A 12mo leaf, carrying a page of ink notes of classical names in this second hand, is loosely inserted. This offprint is excessively scarce: the only copy traced on either COPAC or OCLC WorldCat at the Boston Athenaeum.