Featured Ten-Inch Cast-Iron Sphere, Apparently Hollow: Cannonball?

@springfld.arsenal

As nearly as I can measure; 10" within ~1/8".
A 10" sphere has a volume of ~524 cubic inches.
Cast Iron weighs ~0.254 lb/cu. in.
Sphere should weigh ~133 lbs if solid.
Sphere actual weight: ~61 lbs 6 oz.
So this sphere only weighs a little less than half (0.4615) what it would if it were solid.
That tells me the hollow is a sphere with a volume of ~282.2 cu in., which matches closely with the phantom weight of ~71.2 lbs.

The sphere is featureless, save for the surface rust an' pitting. There are no obvious ports or plugs (I've looked it over carefully) that would allow powder or shrapnel to be admitted into the hollow.
I've had it stored in an outside room at my son's place, but he took one look at it an' insisted it be removed, as he considers it may be filled with powder or other explosive material. So it's on my deck.

All of this is preamble to my question: Is this a cannonball?
If not...what in the world do I have?
Then there's the problem of how an iron sphere is cast with a hollow core?
I know I'm missing something important here...but hope y'all will chime in an' relieve my puzzlement. Thanks for lookin'!

 

No, Davey...it's a green-mould line, from having an enamel bowl inverted over it through the winter. I've looked diligently for any such indicator of construction from halves...an' have found nothing.

 

I think I see a weld line under that green ring. Could be the power of suggestion .

 

I think I see the band you three guys mention in the bottom image, lower left, but I think I see two very light letters.....maybe an 'a' and a 'B' in the purple upper left!!

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Could it be some type of anchor? Rope tied around it?

 

similar
The New Bullet And Shell.com

 

Could, I suppose, be re-purposed in an emergency situation...but 2 things about anchors, Laura; they tend, even when purpose made, to get fouled...lost on the bottom. An' if made for use as an anchor, it would certainly have a rope or chain purchase-fitting...of some sort.

 

I have a bunch of glass Japanese fishing floats and there were no fitting - just strategically wrapped and tied.

 

Yes, I'm familiar with the exquisite netting around those Japanese glass floats...they're highly collectable here an' elsewhere, especially along the west coast.

 

During the ACW there existed cored shot, lighter than solid shot of same diameter. I can’t recall exact tactical purpose. If you want this compared to official specs, get me the exact diameter using accurate tools. For a 10” gun it will need to be like 9 7/8 (can’t recall zakly.). If 10 or slightly more it isn’t a cannon shot. Windage requirement made sure all round projectiles were a bit under the actual caliber (10, 9, 8, …). https://civilwartalk.com/threads/what-is-a-cored-shot.131205/

 

Thank you!
As closely as I can measure, the diameter is very near ten inches...but given your comment about windage requirements, it's worth trying to get a more accurate diameter, checked in several places.
It's wet out there now, an' will be, off an' on, for the next week or so.
If, on the other hand, it is exactly, or slightly over, 10 inches...what would it have been made for? Everyone I've shown it to here is, like me, completely without a reasonably sound idea about its purpose otherwise.
A very informative link, an' thanks for that!

 

I can’t address such an item if it is 10 in. Or 10 Plus, to me it wouldn’t be ammunition, unless of course you know it comes from some foreign country with appropriately different standards of measure.

 

I had a solid cannon ball from the presidio in San Francisco it was around the same size but solid. You sure the thing you got is empty, because they filled some with explosives.

 

I am led to believe it is empty...because after very close examination I (an' several others) can find not even a hint of a port, or remnant of one, that would have allowed explosive material to be inserted into the sphere.

 

Uh oh’. The dreaded Abbie Normal! (Ya had to have seen the movie!)

 

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I have 4 of them in a fountain in my front yard, 2 are large and 2 are smaller. Relatives run a dairy ranch in Pt Reyes, California, now the National Sea Shore. The Dairy started in the 1800’s and covered about a mile of coast line the beach was private property by old Spanish land grants. The glass floats would wash up on the sand from time to time and the only access was a locked gate and a long dirt road to the dunes and water, since the mid 1960’s it’s been public.

 

I suppose it’s possible it with a dozen others could have been used in some large ball mill for mineral recovery. You sometimes find smaller versions metal detecting around old mining operations.

 

Here’s some,