Carnegie noted that Scottish lochs were created by just constraining the flow of water. Butler and the rowing team had just such a scheme in mind to create an artificial lake. With Carnegie's permission, Butler contacted a building firm in his home town and obtained an estimate of US$118,000 to construct a lake. Lake Carnegie and the purchase of hundreds of acres of land resulted from this meeting. It was while employed by Carnegie that Butler supervised the construction of Carnegie's mansion on Fifth Avenue, which was designed by Babb, Cook, & Willard and is now the Cooper-Hewitt Museum, but he and Carnegie differed and Butler left his employ in 1905. From 1905 until 1907 he was in California and again in the early 1920s when he was living at Pasadena and Santa Barbara. He may therefore have missed the opening of the lake in 1906 that was three and a half miles long and eight hundred feet wide. It was reported that President Wilson tried to later persuade Carnegie to give funds to Princeton but he was told that he had already given a lake. Wilson is reputed to have said, "We needed bread and you gave us cake." In 1918, Butler's association with Carnegie led to him being invited to witness and record the 1918 Solar eclipse that was observed from Baker City in Oregon. The expedition was organised by the U.S. Naval Observatory and included Samuel Alfred Mitchell as its expert on eclipses. Butler noted later that he used a system of taking notes of the colours using skills he had learnt for transient effects. Usually a sitting for a portrait took two hours but an eclipse would take just over 112 seconds. It has been noted that he had painted Carnegie thirteen times and like the eclipse he could never keep still to allow Butler to make considered notes. His revived interest in physics led to his 1923 book "Painter and Space" which coincided with his second visit to a solar eclipse. He also created pictures of planets that were as seen from one of their moons. His last known eclipse visit was in 1932. Butler is known particularly for paintings of seascapes and for his views of the eclipse of the sun, but he also painted people and landscapes. Butler also designed an Astronomy Hall for the American Museum of Natural History. Butler's paintings of solar eclipses were on display for many years at the Hayden Planetarium at that museum. Butler died in Princeton in 1934 near the lake that he had organised for their rowing team. His work can be seen at the Metropolitan Museum of Art, the Smithsonian American Art Museum, American Museum of Natural History and of course Carnegie Lake.