Before we get into the specifics of individual artillery types as used in the American Civil War, it does not hurt to understand how they were made. The materials having been previously described, what was the basic procedure used to convert the raw component metal into an artillery piece?
In the case of both the bronze guns such as the Napoleon and the cast iron Parrott, an outer flask is created out of sheet metal bolted together. Inside this flask a mold is made of hard sand surrounding a wooden model. Once the mold is created it is split to remove the model and then reassembled for casting. This mold has space for extra material at the muzzle end to provide extra metal to ensure the piece remained at proper size as it cooled. This section was called the "dead head."
When it was time to cast, the mold was typically placed into a pit near the furnace where the metal was melted. With the molten metal poured into the mold as quickly as possible, it was filled to the top. As it was filled the molten metal was agitated with a pine stick with the intention of forcing impurities to the center. When the pour was finished, the intended artillery piece was allowed several days to cool.
Once cool the piece was removed from the mold and the dead head was cut off. At this point cutters and reamers were applied to the muzzle until the bore was cut to the proper depth and size. If all went well during casting, this also removed the impurities. As this is going on, most of the exterior is finished by hand chisels. The exception to this finishing are the trunnions, which are the parts that protrude from the sides of the cannon. These are turned on a large lathe after the boring work is completed until they are straight and true, allowing the piece to pivot on its center with relative ease. At this point the vent hole is drilled out.
With the Parrott an additional part is attached, the reinforcement band around the breech. Made of wrought iron and thus stronger than the cast iron of the tube, this was heated until red hot to expand it and then the band was forced onto the cast barrel. Once in place, the band cooled and increased the strength of the breech.
The 3 inch Ordnance Rifle was the other common artillery piece and it was produced differently. Instead of being cast the iron was welded in place. It is easiest to take the description from the original 1855 patent.
"A pile of wrought-iron rods 7/8" x 7/8" x 4 1/2 feet were welded together to form a mandrel. A long bar 3/4" x 4 1/2" was wound spirally around this by revolving the lathe. Three successive layers were thus applied to the mandrel, each layer spiraling in a direction opposite to the previous one. A thin layer of staves was applied to the outside, and a plug driven in to form the breech. Welding heat was then attained and the mass was rolled out to the length of seven feet. Trunnions were welded on and the gun was bored and rifled from the solid."
This process made the strongest and safest (for the gun crew) artillery piece used in the Civil War. Only one is known to have burst in the course of the entire war, as opposed to dozens of Parrott rifles. To give perspective, all artillery pieces were "proof" fired to ensure they could take the strain of service. When initially produced they were tested to the point of failure. When the Ordnance Rifle was tested, it was eventually destroyed by stuffing the bore with a total of seven pounds of Black Powder and 13 Projectiles. Only then did it fail.
Next time in our discussion of artillery we will begin to examine the artillery itself, strengths and weaknesses.
-Corporal
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