Q: About 25 years ago, I bought a solid copper lithographic printing plate at a yard sale. It weighs 15 pounds and is 10 by 6 1/2 inches. The image is a navigational aid for the “Mahukona Harbor and Approaches” of Hawaii. It’s also marked “#4101 C&GS.” Does the plate have any value?
A: Copper printing plates like yours were made to print surveying charts for the U.S. Coast and Geodetic Survey (C&GS). The survey that resulted in the manufacture of your plate was done in 1910. Today the U.S. surveying agency, which manages a national coordinate system for mapping, charting and other engineering applications, is called the National Geodetic Survey. It’s part of the National Oceanic and Atmospheric Administration of the U.S. Department of Commerce. Survey plates as old as yours and in excellent condition can sell for $150 or more.