In 1879 he bought a new mirror from Calver to mount in a larger Newtonian reflecting telescope he was building. He used it to make further observations of satellites of Mars and Saturn, and was able to see Saturn's moon Mimas and show that the ephemeris of its orbit was incorrect. With this instrument he also obtained a photograph of a comet in 1881, C/1881 K1. His most notable work with this telescope were the long time exposures he made of the Orion Nebula between 1880 and 1884. His 1883 photograph of that nebula for the first time showed photography's ability to record stars and other features invisible to the human eye. Common noted of his own photographs that: