1760-67: The Life and Opinions of Tristram Shandy, Gentleman, by Laurence Stern, in 9 volumes
Volumes 5, 7, and 9 are signed by the author. Volumes 1 and 2 are 4th edition, Volume 3 is 2nd edition, and Volumes 4-9 are 1st edition, as well.
1776: An Inquiry into the Nature and Causes of the Wealth of Nations, in two volumes, by Adam Smith
The inscription is believed to be from the author himself. Has been in the Gettysburg College library since the 1880s and has been rediscovered by library staff twice (once in the 1930s and again in the 2010s).