This four book series ( http://henryaltemus.com/series/series192.htm) was published between 1914 and 1932. Here is a new picture for the data base. The Format 3 book was published between 1924 and 1932. Below the dust jacket for this format along with the book is pictured. As is frequently the case, the jacket matches the cover of the book.

Format 3 Dust Jacket

Format 3