Printed cards relating to Hammer's experiments in telephonic and phonographic transmission

A remarkable experiment in phonographic and telephonic transmission of sound between New York and Philadelphia, printed card, recto

A remarkable experiment in phonographic and telephonic transmission of sound between New York and Philadelphia, printed card, verso

A remarkable experiment in phonographic and telephonic transmission of sound between New York and Philadelphia, printed card, recto

A remarkable experiment in phonographic and telephonic transmission of sound between New York and Philadelphia, printed card, verso

A remarkable experiment in phonographic and telephonic transmission of sound between New York and Philadelphia, printed card, recto

A remarkable experiment in phonographic and telephonic transmission of sound between New York and Philadelphia, printed card, verso

A remarkable experiment in phonographic and telephonic transmission between New York and Philadelphia, printed card, recto

A remarkable experiment in phonographic and telephonic transmission between New York and Philadelphia, printed card, verso