The bottom of the address is c/o SRSN
Slippery rock state normal school, a teachers college.
http://digital.klnpa.org/cdm4/result...=/postcard&t=s
The two marks under the message look like two trees underlined.
Maybe some sort of rebus puzzle? The obvious would be Underwood, but I can't find an Underwood with the Pirates, so that's probably not it.
Steve B