This cup plate has a small round image in it's center of the USS Constitution also known as "Old Ironsides" which was commissioned to be build in 1794. The next row has two shields, alternating with two stars encircled. The rim is 23 bold scallops with two small points between. The design die of this variety seems to differ in contour with the ship raised slightly above the table-ring, so that the plate has a tendency to rock. It's origins is believed to be Sandwich, it's rarity is listed as common.
Cup plates were very popular from the 1826 into the 1850's in America. They performed many purposes, as a coaster for a tea cup; they helped prevent tables from being marred, and also kept the table linen clean, and acted as a cooling medium to the hot cup of tea.
LR#610-A is a clear EAPG cup plate from the from the "Ship Group" section in the book "American Glass Cup Plates" by Ruth Webb Lee and James H. Rose. The photograph is on page 330 and the description is on page 334. The diameter is 3 1/2". There are two visible crack lines which cannot be felt, other than that it's in pretty good condition, considering the age of the item.