Cascabel

Common to all cannon, the end where the projectile comes out is called the muzzle and the other end is called the breech. The cascabel is a subassembly of the breech and is only found on older cannon which load powder and projectile through the muzzle. Cannons destined for the Army have a cascabel in the shape of a knob. For naval use, a breeching jaw was cast and machined in place of that knob.

York’s naval cannon has breeching jaws and within the back of those jaws is a pinned block that defines a large, traverse hole. Arresting ropes attached to the ship were run through this hole to deal with the recoil of firing and pull the cannon back into position for the next shot. Behind the large hole is a smaller hole where a loose fitting, internally threaded block was attached. A long, stout rod called the elevation screw was threaded through that block with its bottom end being loosely captured by another fitting attached to the cannon’s mount. This elevation screw could rotate but would not move vertically. On the top end of the elevation screw was a hand wheel and by turning the wheel one way or the other, the muzzle of the gun would either be pulled up or pushed down for aiming purposes.  

The cannon’s own internal foundry number (250) can be seen stamped on the top of the cascabel.

Trunnion

Cannons of this era have two cast and machined cylindrical protrusions on either side of the barrel called “trunnions.” They were used as mounting and pivoting points and the foundry number (250) can be seen stamped on the side of the right trunnion’s shoulder.

“1863” is the year the cannon was manufactured. “100 Pdr.” (Pounder) indicates the maximum weight of the largest projectile the cannon could shoot. The “6.4” stamped below the projectile weight is the bore’s diameter in inches. The cast and internally threaded front sight base is seen at the top center.

On the left trunnion face there is stamped the letter “P” (Proofed) with the initials of the Navy Ordnance Inspectors RBH stamped beneath. RBH stands for Robert B. Hitchcock who inspected cannons for the Navy in 1850, 1851, 1857 and 1861 to 1865.

York’s cannon has a preponderance of around 90 pounds. “Preponderance” is an artillery term that indicates how much heavier the back half of the cannon is than the front half. In other words, from the center of the trunnions to the very back end of the cannon weighs about 90 pounds more than from the center of the trunnions to the front end of the barrel or muzzle.  

The Band

This type of cannon has a “band” and that is the large cylindrical part of the back of the barrel. The purpose of the band is to contain the pressure of the exploding 10-pound black powder charge inside the barrel.  

Stamped on top back of that band are the initials of the cannon designer “R.P.P.” – Robert Parker Parrott. The cannon’s registration number “No. 206” is followed by one of the three “line of metal” center lines cut into the iron while the cannon is still in the metal lathe. Two are visible in this picture - the front being a bit shorter than the one between the “6” and the "9.” The third is cut into the top of the muzzle. “9672 lbs.” indicates the cannon’s weight. On the rear right edge of the band is a round eye used to secure the rear sight which had a sliding aperture for elevation. 

Cast on the inside of the right trunnion we can see the threaded forward sight block with the cannon’s registration number 206 stamped on the top. To the left of the sight block and stamped in the middle of the barrel is an anchor which identifies the cannon as a naval artillery piece. 

More toward the middle of the band we see three holes, two larger with internal threads and one smaller and more forward called the “vent.” The two larger holes were used to secure a device called the “lock.” When the order came to fire the cannon, a lanyard set the lock’s action in motion causing sparks to ignite a small charge which went down onto the vent. The gunpowder in the vent ignited and went directly to the 10-pound, black powder charge at the end of the cannon’s bore under the band. When ignition occurred, a fast-moving plume of hot, white smoke shot straight up out of the vent followed very closely by the cannon’s loud report.   

Manufacturing methods

Parrott Rifle cannons were manufactured with a combination of cast and wrought iron. The cast iron barrel made for an accurate gun, but was brittle and could fracture. To help contain the pressure of the 10-pounds of exploding black powder, a long, 4” square wrought iron bar was forge welded into a spiral to make the reinforcing band. Looking somewhat like a spring with the ends cut square, this now solid, cylindrical fabrication was machined to tolerance, inside and out and heated red hot. The barrel was then lowered down into the expanded hot cylinder and the whole assembly was rotated as water was poured down the muzzle. This method of cooling allowed the hot and expanded wrought iron cylindrical band to shrink and attach itself uniformly to the cast iron barrel. Other cannons had been designed this way, but securing the band on the barrel was Parrott’s innovation. His method overcame some of the shortcomings of the earlier models. By the end of the Civil War, both the North and the South were using this type of gun extensively.

Although accurate, as well as being cheaper and easier to make than most rifled artillery guns, the Parrott had a poor reputation for safety and was shunned by many artillery men. This type of artillery piece was discontinued around 1890 for safer cannon models.

Patented 1861

Captain Robert Parker Parrott was a West Point graduate and native son of Lee, New Hampshire. Parrott invented a different manufacturing process to attach the reinforcing band to the barrel. He resigned from the service in 1836 and became the superintendent of the West Point Foundry in Cold Spring, New York. Parrott went on to create this cannon bearing his name and corresponding projectile in 1860. He patented the process in 1861. Parrott's patent authorized the manufacturing technique which is signified by the “Patented 1861” faintly stamped on the back edge of the band.

Rifling

Cast iron is brittle and when under repeated stress from black powder explosions pushing heavy projectiles down barrels made from that material, those barrels sometimes had the nasty habit of fracturing and literally blowing apart. Putting excessive elevation on the barrel would cause even more stress because of the extra effort it would take to propel the heavy projectile out of the barrel at a steeper angle.

In York’s cannon barrel, there are 9 “grooves” cut in a right-hand twist, lengthwise along the bore. The grooves are separated by 9 uncut parts of the bore called “lands.” This combination of lands and grooves is called “rifling” and is found in all modern hand and long guns except for the shotgun. In an attempt to alleviate as much as possible the stress imparted to the barrel by firing heavy shells, Robert Parker Parrott used rifling cut with a gradually increasing spiral pitch. More commonly known as “gain twist,” the rifling was cut straight at the bottom of the barrel, just in front of where the 100-pound shell was seated against the 10-pound black powder charge.

When the black powder exploded, it would expand a metal skirt on the bottom of the shell causing it to push hard against the cut rifling. As the heavy projectile was propelled down the barrel, the slowly increasing pitch of the rifling would cause the projectile to gently accelerate its rotation. The gradual increase over the length of the barrel would minimize the stress imparted to the cast iron by the exploding black powder. Maximum pitch of the rifling was at the muzzle where the shell, as it left the barrel would achieve the desired 1 turn of rotation for every 18 feet of flight. The projectile rotating on its axis as it goes down and leaves the barrel of the gun, adds greatly to the accuracy of the shell, much like a properly thrown football.

By 1906, the cannon’s bore had been filled with concrete leaving just enough of the rifling grooves for us to see. Note one of three “line of metal” centerlines cut into the top of the muzzle edge while the cannon was still in the metal lathe.