One of the mysteries that was unsolved at the time of our first exhibition of American Decorated Publishers' Bindings 1872-1929 was the artist responsible for the cover of The Arncliffe Puzzle. It has always been one of my favorites, with a hooded figure blending from within to outside a red-orange circle, holding a gold question mark like a sickle in one hand, and its gold dot like a ball in the other. It is one of the best examples of an artist playing with the picture plane on a book cover, using both color and imagery to achieve the effect.
The author is not identified on the cover, another mystery. It says "By the author of A Mysterious Disappearance." That one is solved on the title page, where Gordon Holmes is named. But with no designer's monogram and no comparable covers to help, the artist remained unidentified.
The author's identity was not exactly a clear giveaway, despite the title page attribution. Gordon Holmes was a pseudonym used by more than one author. It was shared by Matthew Phipps Shiell (who also wrote as M. P. Shiel) and Louis Tracy. They also collaborated under the name Robert Fraser. A quick search of WorldCat revealed that in later editions the authorship is attributed to Louis Tracy. But the cover artist was not identified.
More recently, in researching the design influences of artists of the period, I acquired a copy of Decorative Design by Joseph Cummings Chase [Wiley 1915]. This cover is illustrated on page 37, and the design attributed to J.C.C.
Joseph Cummings Chase
The Arncliffe Puzzle
by Gordon Holmes (Louis Tracy)
New York: Edward J. Clode, 1906