There are actually four different baseball issues by S.F. Hess, all dating to 1888 as follows:
N321 - California League (color; remaining three being actual photographs)
N333 - Newsboys League (features boys from 8 different cities/newspapers)
N338-1 - California League (photo)
N338-2 - Major League players (primarily NY Giants)
They are all rare with the photographic cards (N333, N338-1, & N338-2) being a bit tougher than the N321s. Some of the N338-1 cards have striking outdoor poses but in general the N338-2 cards command the highest value due to subject matter (major leaguers). I've been waiting for an example of Charlie Getzien to surface for many years with no luck.
The SGC population report (link below) shows only a handful of N338-2 players have more than one graded copy (many with zero). Buck Ewing is the most "common" at 3 examples graded. This is rare territory that actually may hurt value since no one can expect to complete a set. A type card is all most with interest will attempt.
http://www.sgccard.com/PopulationRep...px?setid=10104