That of a cylinder, it being the only mortar whose chamber is of this shape. 11. How are mortars mounted? On beds of wood or iron. [Sidenote: 33]] 12. What is the object of mounting mortars on beds in preference to wheel carriages? On account of the high elevation at which they are usually fired, when the recoil, instead of forcing the piece backwards, tends to force it downwards, and this tendency becomes so great at the higher angles that no wheel carriage could long sustain the shock. 13. What is the entire length of each mortar? 13-inch, 53 inches; 10-inch sea-coast, 46 inches; 10-inch siege, 28 inches; 8-inch, 32.5 inches; stone mortar, 31.55 inches; coehorn, 16.32 inches. 14. What are the weights of mortars? 13-in., 11,500 lbs.; 10-in. sea-coast, 5,775 lbs.; 10-in. siege, 1,852 lbs.; 8-in., 930 lbs.; stone mortar, 1,500 lbs.; coehorn, 164 lbs.; eprouvette, 220 lbs. 15. What are the weights of the different mortar beds? 8-in. siege, 920 lbs.; 10-in. siege, 1,830 lbs.; coehorn, 132 lbs.; eprouvette, 280 lbs. 16. What are the diameters of the bores of the stone, coehorn, and eprouvette mortars? Stone mortar, 16 inches; coehorn, 5.82 inches; eprouvette, 5.655 inches. 17. What is the length of the bore, exclusive of the chamber, of the different mortars? 13-in., 26 inches; 10-in. sea-coast, 25 inches; 10-in. siege, 15 inches; 8-in., 12 inches; stone mortar, 19.8 inches; coehorn, 8.82 inches; eprouvette, 11.5 inches. 18. What is the length of the chamber of the different mortars? 13-in., 13 inches; 10-in. sea-coast, 10 inches; 10-in. siege, 5 inches; 8-in., 4 inches; stone mortar, 6.75 inches; coehorn, 4.25 inches; eprouvette, 1.35 inches. [Sidenote: 34]] 19. For what purpose is the eprouvette used? For determining the relative strength of gunpowder. 20. To what purpose is a stone mortar applied? To throw stones a short distance, from 150 to 250 yards; and also 6-pr. shells from 50 to 150 yards. 21. In what manner are the stones disposed in this mortar? They are put into a basket fitted to the bore, and placed on a wooden bottom which covers the mouth of the chamber. 22. What use is made of coehorn mortars? They are fired either from behind intrenchments like other mortars, or they may accompany troops in effecting lodgments in towns and fortified places. 23. What kind of projectiles are thrown from mortars? Shells, fire-balls, carcasses, and stones. 24. How rapidly may siege mortars be fired? At the rate of twelve rounds per hour continuously; and in case of need with greater rapidity. [Sidenote: 35]] PART I. SECTION VI. SEA-COAST ARTILLERY. 1. How are _Sea-Coast_ pieces mounted? On barbette, casemate, flank-casemate, and columbiad carriages; and the carriage upon which the mortar is mounted—called its _bed_. These carriages do not subserve the purpose of transportation; the barbette carriage may, however, be used for moving its piece for short distances, as from one front of the work to another.