Photo foresics on a burst Parrott Rifle

While everyone else is combing through crowd photos looking for glimpses of Abraham Lincoln, I’ll stick to the photos of guns and beach sand.  Back a few years when discussing the big Parrott rifles from a technical and service history standpoint, I left open discussion about the type’s tendency to burst, looking for a good “150th” setting to discuss.  Well that time is now.  Major-General Quincy Gillmore, in a lengthy version of his official report published in 1865, noted that six 8-inch and seventeen 6.4-inch Parrotts burst during the summer and fall operations on Morris Island (not including the failed 10-inch Parrott from Battery Strong).

Consider this photo from the Haas & Peale collection, taken on Morris Island sometime in the summer of 1863:

burst_100 pound Parrott

This is a 100-pdr, or as I prefer 6.4-inch, Parrott rifle which burst along two lines – one across the barrel right at the trunnions and the other laterally back through the breech.  The gun broke into three major pieces, excluding the band, with the chase and two halves of the breech.  One of those three is either hidden from view or already discarded.  Looking closely, there is evidence of secondary cracks.

BurstParrott1A

I’ve looked over the bore a time or two, but not seen any marks worth chasing down.

BurstParrott1B

That’s unfortunate, as there are several listings of burst Parrotts on Morris Island which contain details for each particular piece by registry number.

Far more interesting than the undamaged muzzle is the breech.  With that portion of the gun cleaved in two by the explosive force, we can see some details of the weapon that we don’t normally get to view.

BurstParrott1C

Notice the thickness of metal from the bottom of the bore back to the stub of the cascabel.  Yet, in comparison the walls around the top and bottom of the chamber are not as thick.

BurstParrott1D

The rifling shows up clearly in the photo.  It starts a good distance from the bottom of the bore allowing for the seating of the charge.  The first few calibers of rifling are straight, conforming to Robert P. Parrott’s increasing-gain rifling pattern.

The band, or at least a portion of it, stands behind the gun.

BurstParrott1E

Gillmore’s report included plates, recorded by Captain Alfred Mordecai, Jr., showing the bursting patterns of various Parrott rifles.  I’ve looked through them hoping to find a diagram that matches this gun.  But I’ve found at best an 80% match:

BurstParrottPlXXVII

Gun with foundry number 736 burst after 514 rounds, firing a charge of 10 pounds and an 80 pound projectile.  The particulars around the breech are not a perfect match to the photo.  Then again, maybe Mordecai was a bit generous with the diagram.  But if this is a match, the gun in the photo was delivered to the Army sometime in December 1862.

In his report, Gillmore suggested there was a pattern among the burst Parrotts.  Sensing the reinforcing band was sufficiently strong, he pointed to defects in the cast iron of the gun barrel. On the other hand, I don’t see anything in the photos or diagram which would lead to a conclusion about casting defects.  The break, which actually is rather clean for a burst cast iron gun, is more indicative of a stress failure.  Then again, I have a degree in history and not physics.  However, to my point Gillmore reported an alarming number of premature shell explosions for these Parrotts.  And that is something the guns were not designed for.

Gillmore suggested the band could be extended a few calibers more in length, and be screwed onto the gun instead of slipped on.  In addition, he suggested that, “the gun be cast hollow, and rifled with a uniform twist, or a twist of uniform pressure against the bands.”   Not saying Gillmore’s suggestion carried all the weight, but all large caliber Parrott rifles received after 1863 were “to be cast hollow and cooled from the interior.” The screw-on reinforcing band and uniform rifling were not adopted, however.

Before bringing up the charts and tables to fully analyze the Parrott’s endurance, let me discuss the background and setting of the photo above.  In the background is a row of sling carts and siege limbers:

BurstParrott1F

This could be about anywhere on the south half of Morris Island, where guns were staged before moving to the front.  But the presence of a steamer in the background argues this was the south end wharfs on Morris Island.

BurstParrott1G

Given that location, this photo could date to about any time during the operations on Morris Island.  While the photographers might have simply thought this burst gun would make a good photo essay (and great for future historians to dissect in blog posts, I add with cynicism).  But I would also suggest this photo was taken at the request of the Army officers.

The Morris Island Campaign was the first prolonged combat operation using these big Parrotts.  The failure rates were, while not prohibitive, alarming.  Questions about the guns turned into accusations of some sort.  A photo of a failed gun could be worth the proverbial thousand words during such an exchange.

Photo credit: Hagley Museum and Library collection of Haas & Peale photographs, ID Number 71MSS918_027.tif

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2 responses to “Photo foresics on a burst Parrott Rifle

  1. Pingback: Exposion in the turret: Parrott Rifle problems afloat | To the Sound of the Guns

  2. Pingback: “Ninety-five tons of loyal complements”: Bombardment of Charleston continues | To the Sound of the Guns

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