Nasmyth, a Scottish engineer known for his invention of the steam hammer, combined an avid interest in astronomy and photography. Carpenter was an astronomer at the Greenwich Observatory. Together they constructed plaster models of the lunar surface. They photographed these models using raking light, with light rays coming from oblique angles, to simulate the shadow effects one might perceive on the surface of the Moon through the telescope. In 1610, Galileo discovered mountains on the Moon with the benefit not only of the telescope, or “perspective tube,” but also of an artistic tradition of chiaroscuro, the handling of light and shadow. With the perspective exercises of Pacioli, Leonardo or Sirigatti, students learned to draw the shadows cast by the protruding surfaces of complex geometrical figures. On the Moon, the shadows Galileo observed revealed topographical relief. In the controlled conditions of their photographic laboratory, Nasmyth and Carpenter recreated these effects in detail.