In an attempt to determine the location of the photo, I've looked through some mining literature to see if there were any 10-stamp mills near Visalia, during these years. Fresno County had at least two of these mills in use between 1886-95, i.e. One mill at the Abbey (McNally) mine and another at the Last Chance mine. And Tulare County had at least one mill of this type at White River.
These particular stamp mills would have been used to help extract gold from the rocky ore.
The man sitting in this photo appears to be Asian. Many 19th century miners in California were Chinese.
(Update 4/27/14) I just realized that this photograph is in one of Annie R. Mitchell's books: The Way it Was. (1976), pg. 152. The image in the book is reversed, and it has a fuller view of the stamp mill. This is in fact at White River. Mitchell's book identifies the man on the right as David Bice James. James is an important character in both Tulare and Kern Counties' histories, e.g. Some credit him with starting the Kern River 'gold rush' of the 1850's. (Article about David B. James: PDF file)
Photo postcard view of Porterville, circa 1910. This is at the corner of Putnam Ave. and Roche St., facing east. The three closest homes here on the right side are still at this location. Notice the spelling of Portersville on this card, which was the spelling that the U.S. Postal Service used at this time. "Putman" is apparently just a misspelling of Putnam.
The photograph is by John Bowers of Long Beach, CA. Bowers produced photo postcards of scenes throughout California. On 1/17/1911, Bowers was shot to death by one of his employees, under a rather controversial set of circumstances.
Close-up:
Note the horse drawn carriages on Putnam Ave. and the unpaved street.
"Holt Block" refers to a large two-story building that was on the NW corner of Main and Court Streets.
