I believe that 1) the author is Julien David Le Roy (Julien David Le Roy, 1724-1803), famous French architect and archaeologist, 2) you have an illustration from his book "Les Ruines des plus beaux monuments de la Grèce", published by in 3 volumes, Volume III (where to get your engraving) published in 1794
Le Roy was a good draftsman, he drew illustrations for his books, apparently, sometimes he engraved them (on your engraving is not just "del.", But "sculp."), Although most of his drawings engraved others engravers.
A biography of Le Roy, as well as an example of engraving from the first volume of this book, see
http://en.wikipedia.org/wiki/Julien-David_Le_Roy