I happened across your most interesting site while trying to answer a friend's question. He is an amateur historian and archeologist in Lake County, California, and had posted a photo of a barn bearing an ad for Dr Pierce's Medical Discovery. The ad you have posted from a weekly Chico, California newspaper provides the complete answer to my friend's question, which came down to: "What did Dr. Pierce discover?"

My friend's picture, if you want to see it, is embedded in an article he posted at http://www.chargedbarticle.com/picture_of_the_times.htm :

Here's more info on Dr. Pierce from the Museum of Menstruation, of all sites:
http://www.mum.org/drpierc1.htm