David Roberts first sketched in his journals “on the spot” the vaious subjects which, on returning to London, he transcribed into finished paintings and watercolors. These then formed the basis of the lithographs drawn and printed by Louis Haghe. It is interesting to note that in some instances Roberts’ original drawings were twice or three times the size of the published print, which indicated the skill of Haghe and his assistants in transferring Roberts’ designs onto lithographic stones.
‘Isle of Graia Gulf of Akabah Arabia Petraea,” from “The Holy Land, Syria, Idumea, Arabia, Egypt and Nubia.” 1840’s. Retouched with smudges removed etc. Colored lithograph. Louis Haghe, lithographer after a watercolor by David Roberts. Collection of the Library of Congress Prints and Photographs Division Digital ID # ppmsca.08343. http://www.LOC.gov. Retouched by Gerardm and Durova. In the public domain in the United States because the artists have been dead over 70 years. via https://commons.wikimedia.org/wiki/File:Isle_of_Graia3.jpg
“Temple of Dandour – Nubia.” 1849. . Colored lithograph. Louis Haghe, lithographer after a watercolor by David Roberts. Collection of the Wellcome Trust. Cc0 License 4.0. via https://wellcomecollection.org/works/z23btmt6
“Interior of the Mosque of Sultan Hassan, Cairo, which was completed in 1359, during the Mamluk era in Egypt. Undated. Lithograph. In the public domain because the artists have been dead over 70 years. via http://www.salongen.no/619/
Many if not most of the artist’s work were sold as lithographs. Some of his of Ancient Egypt I used in an earlier post which you might want to look at.