Compared to the single-fire musket, the manufacturing process for this type of firearm was very expensive, which kept their numbers fairly low. The next evolution of the cylinder did not occur until the 1830s. While chemistry was still in its infancy, the development of fulminates as primers for firearm ignition contributed to the invention of the percussion cap. This, in turn, led to the development of the percussion cylinder. As with the earlier flintlock cylinders, the chambers within the percussion cylinders were not bored completely through. Percussion caps replaced the flintlock pans as primers and the drilled touch holes were incorporated within nipples. The nipples were inserted into a recess at the rear of each chamber. The percussion cap was placed over the nipple. These arms quickly incorporated mechanisms that automatically rotated the cylinder, aligning the chamber with the barrel, and locking it in place. Each chamber was loaded in a similar manner as the previous flintlocks, that is, from the front of the cylinder, powder was poured into the chamber and then a bullet was inserted and pressed into place with a ramrod. After the initial invention in the late 1830s of a needle-fire rifle, a revolver was soon developed. This type of firearm used a paper cartridge. It used a long, thin, needle-like firing pin that passed through a small hole at the rear of the cylinder, through the powder, and struck a disposable primer cap that was set behind the bullet. The revolver’s cylinder simply had a small hole drilled at the rear of each chamber. The use of a paper cartridge was a change from the earlier method of charging a firearm. At approximately the same time that the needle-fire system was developed, a pin-fire method was also developed. This method originally used a paper cartridge with a primer cap within a brass base, which quickly evolved into an all-brass cartridge. From the side, a stout pin was inserted into the cartridge above the cap. The gun’s hammer pushed the pin into the cap and set off the primer. A revolver using this method had a cylinder with chambers that were bored completely through with a slight channel where the pin rested. This type of cylinder was first patented in France in 1854. Loading these revolvers was accomplished by moving a loading gate that was mounted behind the cylinder. To remove the spent cartridges, a push-rod was used to back the cartridges out of the cylinder through the loading gate. Cylinders that use these cartridges are what most people envision as modern cylinders.