"Étienne Léopold Trouvelot (1827–1895) was a French artist, astronomer and amateur entomologist. (Curiously, he is most noted for the unfortunate introduction of the Gypsy Moth into North America.)

His drawings of celestial phenomena were so good that the Director of Harvard College Observatory put Trouvelot on staff where he gained access to their powerful telescope. He would go on to produce some 7000 astronomical drawings and publish 50 scientific papers." (Via But Does it Float)
Absolutely phenomenal drawings that I fell in love with instantly. Recent editions of the book are still available to purchase via Amazon in both paperback and hardback.
Buy "The Trouvelot Astronomical Drawings Manual"
Original NYPL source