Principles of Geology

Lyell revised the work through eleven editions by 1872, plus a twelfth posthumous edition in 1875; the volume count changed repeatedly -- four volumes for the third through fifth editions (1834-37), three for the sixth (1840), and two from the tenth edition (1867-68) onward -- so any set that does not collate as three volumes dated 1830, 1832, and 1833, or that carries any edition statement, is not the first edition.