The naming of coins is a purely arbitrary matter, and practice varies widely in this particular. The tendency in modern times seems to be towards employing the names used in the system of accounting. For example, in this country we commonly call our gold coins two-and-a-half-dollar, five-dollar, ten-dollar, and twenty-dollar pieces. The official names, however, are the quarter-eagle, half-eagle, eagle, and double-eagle, these names being derived from the figure of an eagle stamped upon one side of the coin. In England the practice of employing special names is more common, her gold coins being universally known as the sovereign and half-sovereign, and her silver coins as crowns, half-crowns, florins, shillings, and sixpences. With the exception of the two last mentioned all these names are derived from devices on the coins or from old customs. Until comparatively recent times this practice was almost universal, the names of the reigning monarch or of the king who first ordered the coin minted being the most commonly employed. As examples may be mentioned the French Napoleons, the Prussian Friedrich d'ors, and the English George d'ors. Such devices as the figure of an angel, a lamb, a pig, and the rising sun gave names to coins of considerable importance in the Middle Ages. Special names are frequently conferred upon coins by popular usage; as, for example, in this country the names nickel and copper for our five-cent piece and penny. Our twenty-five-cent piece, or quarter of a dollar, is known by various peculiar names in different parts of the country, as, for instance, the "bit" on the Pacific coast and in the South.

Besides the purpose of ornamentation the devices stamped upon coins are designed to serve as means of preventing "sweating" and clipping and of rendering easy the detection of abrasion. The milled or indented edge, the practice of stamping both sides, and the circular form of coins are explained in this way. So far as possible, it is also desirable to use designs which are difficult to copy and which may thus aid in the detection of counterfeits.