Ever heard of a cannononball .. ovoid?
 

This item lacks the basic condition for a ball, as it is not round ... but ovoid.
However the (non professional) seller guaranteed this is surely a cannonball, kept by the family for a long time and having been found in a place where actually plenty war confrontations took place, both internal and Napoleonic.
The weight and average diameter coincide with an 18 pounder.
Byt i don't think this thing could be fired as it is; neither its deformation could be achieved by rolling on the ground after being shot ... it wouldn't become so perfectly ovoid.
On the other hand, its texture looks exactky like that of a 18th or 19th century cannonball.
What do you gentlemen think of this?
Ever seen one like that?

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Hi 'Nando,

I am afraid I've never seen or come across a cannonball of such unique shape - ovoidal!

What practical sense could it possibly have made?

Fitting and rotating in a cannon barrel? No way, I would say.

The only use I can think of would be throwing it from a catapult but then we would have to seek its "date of birth" in the 14th and 15th centuries. :o :shrug:

Highly interesting piece anyway and one of the unsolved riddles in historic weaponry ... ;)

Thank you for sharing this, and I do hope for some brainstorming from our members!

Best wishes from a completely stumped
Michael

interesting cannonball site:

Linky

my first impression of the faceted surface was it was a worn ball mill ball....

I really dont know much on artillery or ballistics, but I am inclined to go along with Krockew and think it might be a mill ball, from another field foreign to me, metallurgy. I have learned a lot from discussions with you guys and others outside our discussions which have included some that brought up these rather mundane utility type objects, which still in thier own right, have become interesting antique items.

I would think that the ovoid shape would lend better to tumbling action, which would be important in crushing ore.

Thank you all gentlemen, for your input.
I had already been in that link website during my browsing, Wayne.
It appears to me that this is not likely to be a mill ball.
Those spheres are usuallly hardened steel, whereas my example is iron.
I have phoned a cement maker technician; the wearing of mill balls has a smooth texture.
Also i think that a mill ball, worn by continuous random tumbling, would get a alietory shape due to its variable movimentation and not such a regular one, which looks to have been submited to a specific rotation, orientated in a linear direction.
I know nothing about metalurgy either, but probably a steel mill ball woud not degradate through time in the same manner, with such corrugated and scaled look.
A remote probability would be considering that this ball was used for "hot shot", having been "stretched" in its itinerary through the barrel or, not hitting a direct impact target, having rolled on the ground in a regular manner (drum like), before cooling down.
Thing is i don't even know if hotshot was used in Portugal :o .


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Fernando, beautifully explained and nicely done on the research on this! Thank you. As I mentioned, this is way outside my field of study and it's great to learn more on this subject. I had never even thought much on mill balls, and your explanation of the dynamics is excellent.

I of course had never hear of a 'hot shot' in these terms either, though of course hearing the expression in popular usage countless times, never thinking of its meaning. What was the purpose of this as opposed to a regular shot, was it intentional? Can you explain more on this, for myself and those not especially well versed in artillery.

Thanks very much again Nando!!! Really interesting item, you really find them!! and are great at sharing these curiosities here.

All the best,
Jim

Thank you for the usual kindness, Jim.
Hot shot is an artillery resource in which the cannon ball is pre-heated to a read hot condition in a furnace so that, when shot against wooden ships, besides its destructive impact, sets them on fire.
One can imagine the extreme care taken to load these amunitions, to prevent them from setting fire and burst out the cannon itself ... desintegrating all the boys around :eek: .

heated shot was my next guess.

heated shot was as noted used against wooden ships. most fortresses had ovens for heating shot & used well soaked wads to keep the heat away from the powder. firing rates were reduced due to the extra cooling and swabbing required, and as might be imagined, once loaded the cannon had to be fired fairly quickly. accidents did happen. the french built a large number of coastal 'fortresses' consisting of a few guns in earthen embankments, with a small shed for the soldiers and many of these had shot ovens.

i've not heard of it being used in normal land warfare where the shot could roll and be recovered like this one, or i'd possibly considered that. it might have been used in a siege to bombard a town and set it alight, tho i'd expect it to have impact marks.

the health and safety crowd would definitely not allow heated shot nowadays....

Heated Shot

Heated shot furnace

The shape of this ball could also be a result of poor casting.

since cannon balls rusted and scaled in damp storage conditions, the gunners used a shot gauge, a round 'ring on a stick', if the shot passed thru the gauge, it was usable. casting in those days would have been in sand moulds and defective pours would have been common. i'm still surprised that there are no apparent mould lines or sprue marks. cannon balls were never machined post casting other than to knock off the sprues and/or flashing where the metal had been poured. shot was invariably a loose fit. the wadding helped cut down the windage.

Oh yes, it also was:

http://en.wikipedia.org/wiki/Heated_shot


Some of them shooting at ships:

http://www.waymarking.com/waymarks/WM3J37


The largest famous use of hot shot has been performed by the British, during the Gibraltar siege in 1782, against French and Spanish floating artillery:

http://www.clis.com/friends/HotShot.htm

.

Translating an extract of the " History of the first seizure happened in the Rio de Janeiro, in 21st of September of 1711", by Ricardo Bonalume Neto; in which a daring French privateer, René Duguay-Trouin, practiced the first seizure of the Rio de Janeiro, in great style. He captured the whole city and demanded a high ransom.

... Forts are made from stone and they do not set fire if atacked with spherical bullets of iron, shot from cannons with a 2 kilometres reach. However wooden ships, with canvas sails and carrying gunpowder, are highly flammable; and the defender can get hold of a mighty weapon: bullets that can be heated in furnaces and shot still red-hot. The greatest enemy of the attacker is the fire, therefore the fleet must avoid to be exchanging shots with the forts ...
.

In support of the above comment, I have a cannonball recovered off private land at the site of the Battle of San Pasqual, and it too is deformed.

It is not nearly as big as the one above, at a little under 3 inches... possibly used by the Sutter Gun, a provincial small 4-pounder. Shot produced in frontier California tended to be of a lessor quality than what the Dragoons likely would have brought as part of their ordinance.

Anyway, as shown from two perspectives orthogonal to one another - you can see it is still (more or less) "in the round" when viewed from the top-down, but when viewed from the side, well, it's kind of ovoid...

http://img137.imageshack.us/img137/6...cannonball.jpg

Really interesting discussion! and I keep wondering, if this could have simply been an anomaly in casting shot, perhaps the mold became flawed, and the deformed ball was simply tossed aside. Although normally one would presume the iron would be reforged, but maybe this one missed?

Could hot shot have possibly reached near molten state and as noted, deformed as fired? It would seem that at near molten state, no amount of soaked wadding would have kept the powder from accidental detonation...in ths case, probably disastrous, with this notable deformed ball the surviving piece.

On another note, seeking possible industrial instance....

"...here is the very important exhibition of the anonyme society of the forges, usines and bronze, of Gilly (M. Aime Robert, administrator deleague). Excavators, pestle hammers, cranes, locomotives for manufactures and harbours, engines of flattening mills, and thier specialty is the construction of engines to fabricate 'the OVOID CANNON BALLS'.
"Universal Exhibition Paris, 1889"
C.H. Bartels, p.104

While I have no idea of the context here, the mention of these ovoid cannon balls caught my eye, and seen in the industrial possibilty.

I am hoping someone more familiar with manufacturing or engineering antiquities might have some ideas on these. It seems the term cannonball has become so colloquially and metaphorically used, it becomes difficult to search authentic references to them. Its like trying to study something from history or literature and coming up with endless rock band names or songs!

All best regards,
Jim

with the advent of rifled cannon and breech loaders in the latter half of the 19th century, the cannon shot would be essentially cylindrical with an ogival end to reduce air friction and a flattened end carrying the engaging bands on the circumference that would take the rifling (and also allow them to be stored on end so they would not roll around). the ogive at the end would give them an oval appearance. by 1889 i believe that spherical solid shot was essentially obsolete.

even solid round shot during the american civil war was usually mounted in a wooden sabot which would be strapped to the shot with two bands of tin plated iron. these were frequently made up with wadding, and a pre-measured and bagged charge of powder into a complete round of ammunition that could be shoved down the barrel in one go.

the charge would be set off by a primer which was a long tube containing the primer compound and a prick with a sharp end to penetrate the bag, the primer had a pull ring at the other end which would ignite the primer thru friction when pulled - with a long cord. in large artillery and naval guns, charge could be varied by adding extra bags of powder behind the shot.

one easily viewed example is the main 16" gun on the USS missouri used in steven segal's movie 'seige' where they show it being loaded with a rather ovoid shell, followed by six bags of powder. these were fired electrically, but had a chemical primer backup justincase.

a good reference on american civil war era projectiles is the civil war artillery site at this Linky which has photos of hundreds of different projectile types. a very good demonstration firing video is listed under 'cool stuff'. some of the photos in 'cool stuff' show typical confederate and union edged weapons.

This not having to be the case, i have read that one of the risks of hot shot was that the ball could expand its size with too much heat and become problematic for loading.
So why wouldn't the thing also deform while being shot?


Yes, your'e dead right; a famous name came immediately to my mind: Cannonball Adderley. Are you a jazz lover, Jim? :cool:

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I neglected to note that my suggestion on flawed casting was also suggested by Dmitry, and although not established as a conclusion here, seems to remain plausible.

On the dynamics involved in firing, I wanted to thank Krockew for the fantastic and beautifully explained examples of firing and characteristics of these various projectiles. Along with the excellent example shown by Chris of the deformed shot from the battlefield, this material really begins to have fascinating dimension, and its great to learn more about the history of these cannons and firing.

Good example on the expansion of the metal when heated Fernando, and point well taken about heat expansion....really have had to watch tire inflation in travelling through these desert areas in temps up to 120 degrees indexed!!

Actually the more I look at the example Fernando has posted, it seems perhaps it might reflect distortion that might result in forward force as from being fired while extremely hot (as previously suggested). I am wondering if spherical shot when fired would spin or turn, or would the forward force keep it relatively fixed? more physics I guess, but if it was relatively fixed, the material would distort and begin to trail, yes?

On Chris' example, found on a California battlefield, I'm not sure the distortion here would be from heated shot as I dont think they would have used that in ths case. From what I understand, the heated shot was intended for incendiary results, and these would not have been required in a frontier battle where no structures were in place. It would have been logistically improbable as well IMO, so this example must have resulted from other causes. Even an excessive charge in firing would have only created a momentary burst of heat without duration and not been able to distort the shot, I would think.

Yup, definitely a music lover Nando!!! everything from blues to rock to heavy metal (wonder why they never had a group named cannonballs? :)....and yes, I do know who Cannonball Adderly was !! Hard not to, one of the greats.


All the best,
Jim

Sorry to come in late on this one with my .2 cents. Agreed it does resemble an iron cannon ball more than a mill ball. I bought what I thought was a cannonball a number of years ago, but under the grime, it proved to be a steel mill ball ( :mad: ).

I think this is a cannon ball, perhaps used as hotshot and deformed on impact. I have seen (hee hee) balls with flattened sides and bent/deformed bar-shot that struck hard structures.

Still another possibility is that this is a cannon ball made using the 'shot tower' method. I've included two sites explaining this innovative method of making cannon shot, and although one confesses that the balls produced were perfectly round, I beg to differ. Confederate cannon balls were often ovoid, had rough seams, were oblong, etc. In any case, a dropped shot could explain the deformity in times of desparation during war-time. I imagine it would still have fired poorly, though...

http://www.waymarking.com/waymarks/W...er_Columbus_OH

http://www.examiner.com/downtown-bal...pplied-physics

That is really fascinating information Mark!!! I had never heard of a shot tower, nor such a method of making shot and cannon balls. While you might come in late, you do so with a bang!!! :) great stuff!

Thanks for the links on the sites describing these towers too. It seems so odd to fabricate these with such an elaborate method...I always thought these were cast in molds, and it seems like dropping a blob of molten metal would produce all kinds of various shapes, like a rain or tear drop, who would have guessed this method would be effective. I cant get Galileo outa my head on this one:)
It seems odd in the note that the Baltimore tower was still producing shot until 1892, but although rifled guns had come in long before and were technically obsolete, I suppose the smoothbore cannon would have remained servicable ordnance as required and as on hand.

If a ball was indeed oblong or distorted in shape, how would that have effected its firing ? If the spherical shape maintained force and rotation to retain kinetic energy, would the distorted shape cause the shot to slow as discharged, and lessen its range or impact?

It really is fantastic to learn so much more on ballistics and artillery of these times, thank you guys for all this information, and please excuse my attempts at trying to describe my questions with the terminology which may or may not be correct, my exposure to physics and dynamics is limited at best!

All best regards,
Jim

Hi Mark, i'll be damned :confused:
I fully agree with Jim ... last but not least :cool: .
Hardly shot towers were implemented in Portugal: i am still trying to find out if hot shot was used here; not impossible, though.
Not wishing to go off topic, but something that fascinates me and which i have not been managing to spot where i have read it, is that the "pointed" bullet was idealized by Da Vinci in the XV-XVI century, although only implemented just the "other day".
The guy was simply unique.

Howdy Jim...

Given the limitations inherent to a smooth bore and the subsequent lack of rotational velocity (that would have otherwise been imparted by way of a rifled bore), I doubt small variations in (shot) shape would have much more than a nominal impact with regards to precision and accuracy - IMO such variation would likely have been taken into account in the application of artillery tactics at the time.

The "shot tower" method is new to me, and not only interesting but congruent with the deformation of my included example, which has a small and subtle (but noticeable) flat spot consistent with its bottom-biased distribution of mass. This has always given me the impression it either deformed upon impact (unlikely given it is doubtful it would reach a sufficiently high temperature to do so), or had been dropped before it had cooled sufficiently to harden to the point it would resist deformation, something I now realize is inherent to the "shot tower" manufacturing process.

The shot tower method was created in England at the end of the 18th century. The process was used in other countries, but quite popular here in the U.S. Jim, there's a shot tower in Virginia not far from me on the New River. It's a pretty cool site to see from the highway if you are ever passing this way, mate!

elEspadaAncha, your cannon balls could also be more primitively cast iron of the period. They resemble my Rev War American 2 pounders with their "off"- rounded shape.

Yes, Fernando, I definitely agree that hot shot is still in the running. I was unaware before I read this thread that it was ever used against anything but ships. I was going to suggest that a near-molten ball striking ocean water could deform this way, but I'm assuming we know for sure it was found buried on dry land? Likewise, IF it had been used against a ship, one could look for pick-marks to the hot shot where a naval crew would have been working double time with their spiked axes to dig it free from the decking and kick it over the side.( the only way to extinguish these monsters, as buckets of sea water were futile). Fascinating topic, folks.

A few other sites of interest. The first speaks of mill balls. The second shows a few oddly-shaped cannon balls-

http://angloboerwarmuseum.com/Boer12...nnonballs.html

http://www.goldiproductions.com/angl...cs_shells.html

i've never heard of iron cannon shot being made in drop towers, the few references i've seen seem to be by people who assumed too much.

shot towers were for making lead spheres, from bird shot up to small arms sizes. the low melting point of lead and the surface tension of the metal does indeed form spheres, the tear-drop shape so popular in myth is just that, free falling rain drops are essentially spherical, tho easily deformed by external forces.

in a shot tower lead was poured into an appropriate sized sieve or array of funnels selected to provide the correct final diameter, the height of the tower was based on how long it took the lead to harden on the way down where it terminated in a tub of water for final cooling.

after cooling the lead shot was tested for roundness on a tilted table and any that failed returned to the melt. i would guess that large balls of lead intended for case shot and cannister may have lead to the assumption that cast iron could similarly make large cannon balls.

not so, the height of tower required for the higher temp. and larger sized cannon balls molten iron would have been beyond the capabilities of the period. dropping an 18 lb. blob of molten iron into a bath of water is not something i would attempt from any practical height. the 2in. oval grape shot mentioned in the ref. above may have been just small enough for a very high drop tower, but i'd expect a bit more variation.

anyway, one of a few quotes i found on line, it followed a post where drop tower made 'cannon balls' was mentioned:

oddly enough, on a science forum discussing the making of tiny silicon balls for solar cells...

i've owned and fired muzzle loading small arms (pistols/rifled muskets) and cast my own projectiles.

in the pistols (.36 and .44 calibre) i used commercially made shot that was swaged from lead wire or cast, 000 buck (0.36" nominal) from drop towers can also normally be used as the loading process for revolvers usually will trim off any slight oversize, and the forcing cone in the barrel will swage the ball to fit the rifling. rifles would take a cloth patched ball which allowed for some variation in diameter.

the .58 cal rifled musket took a .58 calibre minie ball. one of the shot tower blurbs i read about an american civil war shot tower that mentioned it being used to make cannon balls also said it made minie balls. i tend to doubt that, having cast my own for years.
http://www.worldlymind.org/minie.JPG
minie ball.

note the deep recess in the base, propellant gas pressure would expand the base, forcing the raised portion by the grooves into the rifling. this not only provided for the rotation, but provided a gas tight seal that allowed for more efficient use of the propellant, increasing range. they could be made a bit smaller than the bore, allowing more rapid reloading as opposed to previous round ball/patch combos that required more effort to seat the ball which was engaged in the rifling from top to bottom & thus not only had more friction, but got worse as each shot further fouled the barrel. soldiers were known to pee down the barrels of their rifles in battle to clear the fouling so they could reload. :)

Well...that shoots that theory down. :shrug: I assumed that some of the info I had read was correct that cannon balls were made in this way (included in the tour guide's speal about a local tower I have visited). If the issue is height, some of these structures were massively tall while others weren't. In any case, back to possible hot shot, I guess.

Here's what wikipedia had to say and a list of shot towers around the world, many of them dating to the 1780's-

http://en.wikipedia.org/wiki/Shot_tower

another interesting ref. site:

Solid shot essentials

i noted in there that grapeshot was frequently cast in gangs, ie. like pearls on a string, rather than individually, thus no sprue, and ordinance regs required them to be tumble finished which would have reduced or removed any mould marks and obscured the end details where the individual balls had been broken apart. the oval grape could easily have been produced this way. as it notes, grape did not come into contact with the bore and so could be quite irregular, where odd shaped round shot could scrape or lodge in the bore, damaging it. grapeshot was required to be made from cast iron, tho lead was an accepted alternate. canister, which later replaced grape, used lead musket balls.

Darn, Kronck beat me to the point about the shot tower. I'd also point out that a heated cannon ball, if it was hot enough to deform that much, also wouldn't have an elongated oval shape. It would get flattened by the power of the explosion behind it. More to the point, if it was soft enough to deform that much, it would probably weld itself to the inside of the gun and cause the gun to explode when fired.

I keep looking at the dented surface of the thing. I suppose that could be corrosion that was cleaned off, but I keep thinking that some poor blacksmith got the job of trying to hammer a sub-par cannonball (or a too-big cannonball) into a diameter narrow enough for them to use it with the gun they had. It could also have been a really ugly cannonball that was discarded as too crappy/dangerous to fire.

After all, we've been assuming that it was fired, and I don't see that anyone has presented evidence to support this idea.

Best,

F

Fascinating thread!
How would i guess that the posting of my atypical ball would result in such a treatise on cannonballs.
Hot shot and shot towers would certainly never dream of making part of my vocabulary!
I finally located some data on the use of hot shot in old Portuguese (and Brazilian) coast forts. It was a question of having not browsed with the right term; here they call it bala ardente (burning bullet).
Considering Fearn's reasonable suggestion that this ball was not even fired, having been discarded due to its faulty construction, one question arises: why then wasn't it discarded right after casting inspection, instead of going to take a risky chance to be used in campaign?

I was thinking of a field modification: what do you do when the cannonball is too big for your cannon, and you really need to fire that projectile? "You men, take these hammers and chisels....followed hours later by colorful invectives and a "that didn't work!" Then you leave your failure on the battlefield, to mess with the minds of those who come after you.

Anyway, I was reading a little about hot shot, and the one thing I'm pretty sure about is that they weren't heating the balls enough to deform them. It's hard to do that without a formed air draft and a much hotter fire than they describe.

Best,

F

You will forgive me Fearn but, resizing cannonballs on the battlefield, sounds pretty fictional to me, even assuming the artillery officer had flour in his head, instead of brains.
Even if the issue were to adjust only one ball, which seems rather insolit, it would have to be a sculptor's work, to reshape the thing with the necessary profile ... not a task for rank and file .
More plausibly i would accept this is not an actual cannonball.

Could be, Fernando.

You know how this is going to end, right? Someone's going to have to make a modern cannonball of that particular shape and fire it, just to see if it will fly.

Volunteers?

That´s what i call a brilliant idea :eek: .

Say, you know english better than me; have a look to these extracts:

... The interior of the furnace is lined with fire brick and contains a set of sloping iron rails to hold rows of cannonballs. Rows of iron rods pass through the furnace from one side to the other and are fitted on each end with bolts and "star" braces to support the weight of the shot rails and roof. Cold cannonballs are placed in the furnace and allowed to roll down the inclined rails in rows. The first halls are directly over the firebox at the low end and are heated "cherry red." As they are removed, the next balls roll down into their place and are likewise heated ...

Couldn't the balls prior to the one being heated, start deforming while waiting for their turn, getting the cylindrical shape due to their rolling on the rails ... this assuming that, if the ball being heated reaches "cherry red" temperature, the next ones in the queue must already be half way to it.

... does the cool air tend to reduce the temperature of the cannonball as it flies through the air to the target after it is fired? No. In fact the air friction caused by the cannonball speeding through the air adds to the temperature ...

Something i wouldn't guess!

... The cannonball can even be made to ricochet upon the surface of the water several times without losing enough heat to ignite wood ...

A bit off topic, but this reminds me that, such ricochet method was also used with cold balls, right after portholes were invented and naval artillery could be placed inside the ships decks at sea level. This system brought remarkable advantages for the Portuguese, in naval battles during the discoveries period.

-

re heating cherry red: the thing about these balls is that they're thick. If it's hot on the outside, it almost certainly won't be that hot on the inside.

If it was hot enough to deform, it would droop, not turn egg-shaped. You can run this experiment yourself with a candle, a ball of wax, and something to roll the ball of wax over the flame.

You can also try rolling an egg down a rail, with the long ends on the rails. The egg is going to "want" to spin the long axis, so it's going to twist as it rolls to roll on the short axis. In doing this, it will probably get stuck. So having an oval design isn't going to keep a cannonball on the rails. Round would be simpler.

The thickness of the cannonball will affect how it ignites. For example, if it skips across the water (another place where a spinning round shape works well--see the dam busters), only the part that touches the water will cool, and the heat from the inside will move to the outside. You could get the interesting situation of a cannonball with a cool outer skin hitting a piece of wood, then getting hot enough on the surface to ignite the wood (and this assumes the wood was dry).

Best,

F

just found this manual: (pdf format)

Gibbon Artillery Manual 2nd ed. 1863

rather extensive tome covering gunpowder and how to make it, artillery history,theory, construction in bronze and cast iron for coastal defence, naval and field artillery, alloys used, casting methods, bore turning, fittings, fixtures, tools, methods of employment, loading, firing, cleaning, spiking, unspiking, testing, etc. etc. also includes use with hot shot, heating shot in furnaces, how use of hot shot varied in differnt countries (french used wet hay wadding) use of sabots, rifling, elongated shot, shells, and even mentions electrical measurements of velocity (odd for 1863) as well as the development of gun cotton in 1846 which proved too strong for the guns and small arms of the time so was abandoned in spite of it's smokelessness...

Grrrreat stuff, Wayne.
Thanks for sharing.
I have just kept it in my files.

This procedure was originated by the inmortal Leonardo DaVinci. The result was a predictable perfectly spherical form.

Best

M

[QUOTE=M ELEY]

Still another possibility is that this is a cannon ball made using the 'shot tower' method. I've included two sites explaining this innovative method of making cannon shot, and although one confesses that the balls produced were perfectly round, I beg to differ. .

www.waymarking.com/waymarks/WM5CD3_Fort_Hayes_Shot_Tower_Columbus_OH
/QUOTE]

Guys, I remember seeing as a child some large ovoid metal shapes lying around in Galicia's ports. I believed initially that they were old cannon balls. I was eventually told by a local sailor that in old times, these were used in sailing boats for balance, "to keep the keel down, and the sail up". Somehow, these ovoid metal bodies were either attached under the boat, or in the lowest internal part of the ship. IIRC, they might have been placed near the keelboard housing.

My two "pesetas".

Best

M

see my post no. 24, the writer of that blurb on fort hayes was incorrect in implying cannon round iron shot was made in the tower. they probably made lead balls for cannister and for shrapnel shells, but iron cannon balls, not possible. not enough height for them to cool & solidify before hitting the water, which was to cushion the fall, NOT to solidify the shot. possibly they made round cannon shot there, but if so it was by moulding.

note that the ref. to the baltimore tower specifically mentions the production of iron cannon shot there was by use of moulds.

note the reference link to other world wide shot towers near the top of that page, all of which more correctly only refer to lead shot.

additionally:

In 1783, William Watts of Bristol took out a patent for a process "for making small shot perfectly globular in form and without dimples, notches and imperfections which other shot hereto manufactured usually have on their surface". By pouring lead into a sieve, and letting it cool as it falls, the lead forms into a perfect sphere before falling into a water tank at the bottom.

however, pig iron was frequently used as ballast in wooden ships as you noted, and would have been in whatever convenient sized chunks it was originally cast into. it was stored in the lowest part of the ship to ensure the stability of the vessel by countering any heavy weights (like cannon) above the centre of gravity as well as the lateral pressure of the sails which might have blown it over. (the english 'mary rose' is a good example of what happens when you get it wrong). the captain might on occasion shift the ballast around to 'trim' the vessel to gain an extra knot speed or two, or to improve the stability. cannon balls were of course stowed at the lowest part of the ship and were thus part of the overall ballast.

one of the jobs we had aboard ship, which was there from time immemorial, was to ensure that anything brought on board was stored stably, ballast, fuel, water, food, machinery parts, people, cargo, etc. all have to be stored so as to keep the ship not only level fore and aft, and from one side to the other, but vertically to ensure the stability of the vessel. as a marine engineer, i was trained in not only designing ships, but calculating their stability and how to test that stability. for any who are interested, here is the 'simplified stability testing for small passenger vessels' as an example. the unsimplified version is of course more complex :) Linky to PDF

as a coast guard marine inspector in new orleans, i actually supervised and approved these kind of tests...

No, no, wait! What if the tower was...

Just kidding. I'm one to admit when I'm wrong. Lead shot was made, but I've heard of lead cannon balls in times of desparation. Perhaps with it's low cooling point, they could have been made as such? In any case, our ovoid subject here was not a shot tower ball.

Ballast I suppose seems possible, but I would think that there were much better uses for iron, even pig iron. (early blacksmiths even fashioned tomahawk heads from it). After all, the majority of ballast in the past had been stones, right?

Could this ovoid mass of iron have been used for anything else? A reserve of iron for cannon balls during seiges? As a giant paperweight! :D Just thinking aloud...

Thank you very much for the explanation. Live to learn!

: )