'skip' along the surface of the water. Actual effective combat ranges, they had learned during the Civil War, were comparable to those in the Age of Sail—though a vessel could now be smashed to pieces in only a few rounds. Smoke and the general chaos of battle only added to the problem. As a result, many naval engagements in the 'Age of the Ironclad' were still fought at ranges within easy eyesight of their targets, and well below the maximum reach of their ships' guns. Another method of increasing firepower was to vary the projectile fired or the nature of the propellant. Early ironclads used black powder, which expanded rapidly after combustion; this meant cannons had relatively short barrels, to prevent the barrel itself slowing the shell. The sharpness of the black powder explosion also meant that guns were subjected to extreme stress. One important step was to press the powder into pellets, allowing a slower, more controlled explosion and a longer barrel. A further step forward was the introduction of chemically different brown powder which combusted more slowly again. It also put less stress on the insides of the barrel, allowing guns to last longer and to be manufactured to tighter tolerances. The development of smokeless powder, based on nitroglycerine or nitrocellulose, by the French inventor Paul Vielle in 1884 was a further step allowing smaller charges of propellant with longer barrels. The guns of the pre-Dreadnought battleships of the 1890s tended to be smaller in calibre compared to the ships of the 1880s, most often 12 in (305 mm), but progressively grew in length of barrel, making use of improved propellants to gain greater muzzle velocity. The nature of the projectiles also changed during the ironclad period. Initially, the best armor-piercing projectile was a solid cast-iron shot. Later, shot of chilled iron, a harder iron alloy, gave better armor-piercing qualities. Eventually the armor-piercing shell was developed. Positioning of armament Broadside ironclads The first British, French and Russian ironclads, in a logical development of warship design from the long preceding era of wooden ships of the line, carried their weapons in a single line along their sides and so were called "broadside ironclads". Both and were examples of this type. Because their armor was so heavy, they could only carry a single row of guns along the main deck on each side rather than a row on each deck.