File:Types-of-Shells.jpg

Summary
This drawing is from "The Service of Coast Artillery," by Frank T. Hines and Franklin W. Ward, Goodenough & Woglom Co., New York, 1910, p. 275.

It illustrates the relative sizes of selected shells for the 12-inch coast defense mortar (at left), the 12-inch breech-loading cannon (at right), and a 7-inch and 5-inch shell. The dapper Coast Artillery soldier at center measures a scaled 6 feet tall, from the heels of his stylish pumps to the top of his dress hat.

The abbreviations are apparently CI (cast iron), DP (deck-piercing), and AP (armor-piercing). So-called "torpedo shells" apparently (at least for the mortar) fell out of use during the period 1915-1920. These were shells that were filled with about 130 lb. of powder and were designed (for the mortar) to explode upon contact with the deck of an enemy ship. The 700 and 800 pound shells that were later to become standard for the 12-inch mortar are not shown here.