A nineteenth-century optical toy, the paper peepshow is often considered to be the perfect medium to represent the Thames Tunnel. Yet, this perception overlooks the contradictory sentiments evoked by using the paper peepshow. This chapter, focusing on the period when the tunnel was under construction, seeks to analyze these paradoxes. Admittedly, various features of the paper peepshow can indeed render it a fitting medium to represent the tunnel. Yet, the expanded paper peepshow constitutes a space that is ephemeral, because of its brief existence and its fragility. While the ephemeral quality appears to contradict the monumental impression of the tunnel, this contrast would speak to the nineteenth-century English middle classes’ ambivalent attitude towards technological advancement, embodied in the tunnel.