Public Domain images are 'publicly available' and not covered by intellectual property or copyrights. There are many stock photography websites out there.
A free printable for projects: vintage lavender salt advertisement
Four Vintage Hot Air Balloon Images. Free public domain images of Victorian hot Air Balloons.
The Graphics Fairy: Public Domain Rooster Image
Grandville Illustration from Un Autre Monde 1844
As authors, our clients often refer back to previous writers works. There are plenty of historical fiction, fantasy and steampunk that include characters from previous fiction.