Andrew Bell engravings illustrating the techniques of drawing from the 3rd edition of the Encyclopedia Britannica, published in 1773.
All five prints are for sale on Ebay.
Andrew Bell (1726–1809) was a Scottish engraver and printer, who co-founded Encyclopædia Britannica with Colin Macfarquhar. Wikipedia entry. He is famous for his engravings, but was almost equally well known for his enormous nose. See the pictures at the Encyclopedia Britannica article.
Encyclopedia Britannica Or a Dictionary of Arts and Sciences Compiled Upon a New Plan. 3 Vols original edition.
Encyclopædia britannica: or, A dictionary of arts, sciences, and miscellaneous literature : constructed on a plan, by which the different sciences and ... the form of distinct treatises or systems .. - reproduction.