D. Pedro II was well aware of the shortage of true scientists and naturalists in Brazil. He fixed this problem by inviting foreign scientists to come to work at the Museum. The first to come was Ludwig Riedel (1761–1861), a German botanist who had participated in Baron von Langsdorff's famed expedition to Mato Grosso from 1826 to 1828. Other scientists to come were German chemist Theodor Peckolt and American geologist and paleontologist Charles Frederick Hartt (1840–1878). In the following years, the museum gradually became known so it continued to attract several foreign scientists who wished to achieve scientific stature with their work in Brazil, such as Fritz Müller (1821–1897), Hermann von Ihering (1850–1930), Carl August Wilhelm Schwacke (1848–1894), Orville Adalbert Derby (1851–1915), Émil August Goeldi (1859–1917), Louis Couty (1854–1884) and others; all of them were fired by museum director Ladislau Netto when the Emperor was deposed.