Saturday, August 17, 2013

Durham Cannonball Drama (Part 2)

Last week I posted about a Civil War cannonball, recently recovered by a Durham homeowner, which was destroyed by the city's bomb squad.  I ended by mentioning that it’s possible that what was found and destroyed wasn’t even a cannonball at all!  This may seem like a bold claim, but there are some discrepancies in the news stories that I will point out below to support this hypothesis.

First, let’s talk about the probability that it is the real deal.  As regular readers of this blog probably know, more than 100,000 soldiers fought, marched, and camped in central North Carolina at the end of the war in 1865.  Bennett Place, the site of the largest surrender of Confederate troops during the war, is just a few miles from where the cannonball was found.  It’s certainly not out of the question that a cannonball could be found in the area.  On the other hand, there have been many millions of similar sized iron balls created in the United States that have absolutely no relation to artillery projectiles.  The most common non-cannonball use for these iron spheres would be mill balls, used in a large rotating cylinder to crush and grind material such as raw ore.  Other uses of large iron spheres include fence fixtures, steam engine governors, shot-puts, and crane counter-weight balls to name a few.  Many even have threaded holes (such as filled shot-puts) that can resemble fuse holes in an exploding shell.

(Left)  While they bear a resemblance to solid shot cannonballs, these are steel mill balls used for grinding in cement mills.  (Right) Iron balls are used in a centrifugal force governor to control the speed of a steam engine.  Photo credit here.

Identifying the fuse in the cannonball would be able to identify it as ordinance definitively.  Unfortunately, while several articles on the Durham cannonball mention a fuse, there are no images of the ball before detonation and no mention of the recovering the fuse afterwards.  Without a fuse, the next best way to ID a cannonball would be extremely accurate measurements of the ball’s diameter and weight.  Manufactured ordinance had to meet very exact size standards in order to enter and be fired from the cannon’s barrel safely.  If an iron ball deviates from the measurements in the known ordinance shot tables, it is incredibly unlikely that it was ever intended as a cannonball.  Once again, though, the diameter of the Durham ball isn’t listed in any of the articles I have seen.

Next we’ll look at the weight of the ball.  The Durham bomb squad reported that the shell was a “6 pounder Bormann fused ball".  While the Herald Sun reports that the name refers to the weight of the powder charge, this is incorrect.  The “6 pound” refers to the weight of a solid cast iron cannonball of the diameter used in that gun.  A fused cannonball is not solid, however, and includes a hollowed out cavity filled with lead or iron balls, gunpowder, and a packing matrix.  According to the Ridgeway Reference Archive, a fused 6 pounder ball typically weighs between 4 and 5 pounds.  The Durham bomb squad reported that the recovered ball weighed “about 6 pounds”, but that reported weight is inconsistent with a cannonball with a fuse.  This could be a misstatement by police or a misinterpretation by reporters, but without a more accurate measurement of the cannonball’s weight prior to detonation, we can’t use this method for ID either.

This is a cross-section of the so-called "cannonball" detonated by the Durham bomb squad last month.  The photograph is from the Durham Sheriff's Department via the News and Observer.

What we do have, however, is a cross section of the ball after the controlled detonation.  We can see here a cylindrical hole running through an otherwise solid ball.  Compare this to the cross-section of an authentic Bormann fused 6 pound ball below.  The central “hole” in the Durham ball bears no resemblance to the spherical powder chamber of an authentic 6 pounder shell.  Neither opening in the Durham ball matches with the distinct cross-section of the Bormann fuse hole.  The differences are striking.  Artillery expert Peter George, who has disarmed shells for the National Parks Service and literally wrote the book on Civil War artillery, had this to say:  “Absolutely no cannonballs had a tunnel going all the way through the iron body.”

Now this is the cross-section of a 6-pounder Bormann fused ball.  Note the significant differences from Durham "cannonball" above.  Photo from the Ridgeway Reference Archive.

I’m not an expert, and wouldn’t claim to be, but it appears to me that what was presented as the Durham “cannonball” probably isn’t.  Or, at the very least, there are a few too many discrepancies and unanswered questions for my liking.  Sadly, we will probably never know the answer – the Durham police didn’t return the fragments of the “cannonball” to their finder.  the truth behind this mystery appears to have gone up in smoke!

Until next time, thanks for reading, and God Bless!

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