Signedstamped on envelope: EDMUND SALVAGE CO. P. O. AUDOBON NJ
InscribedStamped on envelope: STOCK NO. 3009 LARGE PORRO PRISM / See Project 17 for How to Use / two to make an errecting system for telescopes, etc.
ProvenanceSalvaged from the Science Center Prep Room, courtesy of Prof. Owen Gingerich.