Mayer patiently introduces children to many of the cutting-edge principles and theories of sound that were circulating in the late nineteenth century, covering topics such as reflection, transmission, vibration, and velocity, along with many newly discovered techniques for rendering sound visible, among them the ubiquitous Chladni figures. But in addition to imparting scientific knowledge, it is striking to note how many of these demonstrations are described in aesthetic terms, as being “beautiful”, “lovely”, or “harmonious”. Mayer clearly perceived both aesthetic and intellectual value in his experiments, and he encouraged his young readers to do the same. After one involving a pendulum that registered the vibrations of different musical intervals, for instance, Mayer advised them to frame the curves produced by the pendulum by fixing them onto glass, which will both “make beautiful ornaments for the window or mantel, and will remind you that you are becoming an experimenter”. Another “very beautiful and striking experiment” involved sprinkling silica powder into a wooden whistle, while elsewhere he describes the pleasure of discovering “beautiful little luminous flowers, like forget-me-nots” that are produced by a singing cone piped directly into a König’s flame. While science in the twenty-first century is often regarded as a dispassionate and purely rational endeavour, in these books beauty and scientific knowledge go hand in hand.