Who invented the Stanhope?

Novelty souvenirs that became popular during the 19th century, these objects (ranging from pens to sewing accessories to jewelry) are unique because of the tiny hidden image placed somewhere inside the object. The image can be found by holding the object up to the light and looking into a tiny hole where the magnified image becomes visible. These images range from landscapes to portraits and are about 1/10th an inch in diameter and 1/4 an inch long. The term "Stanhope" comes from the inventor of the Stanhope Lens, Lord Charles Stanhope (1753-1816) (Note: Lord Charles died before photography had been invented). The name "Stanhope" is somewhat of a misnomer because the actual lens used in the objects known as "Stanhopes" is not actually a Stanhope lens. It is actually called the Codding Magnifier, invented by Sir David Brewster (1781-1868).