1928 Spirit of St Louis cover with an add-on M. Fox hand painted cachet

Scott C10 $0.10 Spirit of St. Louis Air Mail stamp tied to the cover with May 25, 1928 Cleveland Midwestern Philatelic Station cancel on the front and a May 27, 1928 Livingston, Montana duplex cancel with number 1 obliterator on reverse.

Signed M Fox on front by artist, and dated 5/22/85 by artist on reverse.

A couple interesting points on this cover:

The C10 is postmarked one day before the First Day of Issue of the C10a, the booklet pane version of this stamp.

Second, the time on the front postmark is 12 M, missing the A or P for AM or PM.

Neither of these points would add significant value to the cover, but are interesting nonetheless.

(The 1928 Cleveland Midwestern Philatelic Station was a temporary post office station set up for the Midwestern Philatelic Exposition in Cleveland May 21-26, 1928)