Smarthhistory is a Khan Academy partner. The collection maybe searched by time, style, artist or theme. You may use content from this site for your timeline.
This site is a searchable database and virtural museum of art through the 19th century.
Start your research here. This list by a professor at Boston College includes 19th century artists. Artists names are hyperlinked to a page which will take you to images of their work. Choose one artist to study.
There are additional 19th & 20th century artists on this page. This site allows you to search by name, style and movement. You may also choose one from this site who was active in the late 1800s to early 1900s.
ibiblio is a "collection of collections." You may search their databases and will receive links to many resources on different websites about you're artist.
Nineteenth-Century Art Worldwide is a scholarly, referred e-journal about 19th century art: painting, drawing, sculpture, photography and decorative arts. This site may help you find some current research about your artist.