Observatoire de Paris

In 1872, the Henry Brothers, astronomers in the Paris Observatory, inherited a twenty-year-old project of mapping the stars. Over a twelve-year period they recorded the locations of nearly fifty thousand without the use of a photographic device. In 1884 they reached the very dense Milky Way and realized the need for a more exact method of recording the heavens. This led to their construction of a photographic telescope to aid them in their work. Quickly their technology developed to the point when in 1885 they were able to record bodies so faint and distant that they were visible only with their apparatus.