For most of recorded history, comets have played a unique role in culture and science. However, it was really only about 500 years ago that the serious, methodological, standardized observation of comets began, leading slowly to our view of comets as planetary 'worlds' orbiting the sun. After centuries of building our picture of comets through distant observations from Earth, we finally got close-up pictures of cometary nuclei with spacecraft in 1986 (comet 1P/Halley) and in 2001 (comet 19/P Borrelly).
This special telescope is called a Comet Seeker. Built about 1900, it was designed to detect the faint diffuse glow of small cometary tails. This telescope was constructed as a prototype by the Brashear Company for Yerkes Observatory.