Curious stone cannon

[Matchlock]

Curious it is, no doubt; fantastic? Possibly ...

How would it have worked, with two touch holes?!
I'm afraid what really puzzles us is the fact that that piece of cannon must have been crudely altered some later time.

Best,
Michael

[fernando]

It seems as these things were not that uncommon in the Great Wall arsenals.
More uncommon appears to be nowaday's knowledge of how they worked in those days

http://www.greatwallforum.com/forum/...te-cannon.html

I still call them fantastic ... almost unbelievable

[Matchlock]

Hi 'Nando,


This one I completely understand: a breechloader with the interchangeable breech missing.

But two touch holes in line??!!


Best,
Michl

[fernando]

I would surmise that the orifice on the back has a different purpose

[Jim McDougall]

Amazing!!! As Nando says, just when we think we've seen it all.
I think back on the perplexing anomaly of the leather cannons of Tibet, and some of the European attempts at light, portable cannon (I think 'light' and portable eliminated their thoughts of this particular material).

In our minds we think of the powerful charge from detonating powder, and how can these cannon fashioned out of less than expected materials withstand those contained explosions. I am wondering if possibly the gunpowder used in earlier times might not have been as potent as of course more modern types.
With admittedly meager understanding of cannon and firearms I am curious.
Michael, you know I'm looking for your key insight here

Also, would these, like the smaller forms of cannon often seen which seem too small to be effective possibly be for signaling and using lesser charge?

Thank you so much for sharing this Andi! as Nando notes, another for the files. Fascinating!!!

All best regards,
Jim

[fernando]

Well Jim,
It is of general knowledge that gunpowder was infinitely less potent in those days (Ming dinasty), as also the signaling hypothesis must not be discarded; indeed they had signaling systems in the wall, so called Beacon Towers.
But i take it that the explanation for this stone cannon phenomenum must reside somewhere else.
It would be great to get enlightened by some of our forum mates ... the first to find out about it .
Without such explanation, i would even wonder whether the loading breech is not occupied with a (shifting) chamber but simply filled directly with gunpowder and closed with a locking lid ... or some other sort of Colombus egg .

.

[kronckew]

Originally Posted by Jim McDougall

...I am wondering if possibly the gunpowder used in earlier times might not have been as potent as of course more modern types.
...

initially gunpowder was a mechanical dry mix of powdered sulphur, charcoal and saltpeter. much less efficient. vibration in transport would also mechanically separate the components to some extent. knowledgeable gunners would re-mix their powder, if they had time, on arrival at the guns emplacement. fine powdered gunpowder also readily absorbes moisture ands loses it 'strength'.

someone in the 14th c. finally figured out that wet mixing the components mixed the disparate chemicals more intimately, resulting in a more efficient bang for your buck (and was safer).

the mix was ultimately corned - formed into grains of various sizes, the grains were screened to standard sizes, larger sizes for cannon, smaller for muskets, smaller still for pistols and the finest for priming. space between the grains allowed for more rapid and even combustion. the grains, even the smaller priming ones, did not absorb moisture near as much as the fine powder. modern powder is usually made (since the 19c) with potassium nitrate rather than sodium nitrate, and is normally coated with graphite to cut down the risk of static sparking.

i recall someone from the period stating that a charge of 18 pounds of properly grained cannon gunpowder was equivalent to 300 pounds of the old powdered gunpowder.

for more detailed info, see

this linky

[Andi]

Here is a very competent group practically investigating the production of medieval black powder, the Medieval Gundpowder Research Group at Middelaldercentret Nykøbing, Denmark http://www.middelaldercentret.dk/pro...gunpowder.html

They also published their experiments on an Open Source base you will find them here http://www.middelaldercentret.dk/pro...ogkanoner.html

[Marcus den toom]

Matchlock, you are right i noticed this too. But when looking better, i wonder if the other side might have a same hole (the picture is taken from the left, but i notice a similiar chisseling at the right side).
Maybe these aren't touch holes but some kind of carrier holes (maybe with sticks to move the barrel around or up and down?)
just trowing something into the discussion.

[Hotspur]

Originally Posted by Matchlock

Curious it is, no doubt; fantastic? Possibly ...

How would it have worked, with two touch holes?!
I'm afraid what really puzzles us is the fact that that piece of cannon must have been crudely altered some later time.

Best,
Michael

The one in the back to lock the breech block?

Cheers

GC

[Matchlock]

Yeah, most probably.

Cheers,
m

[fernando]

Originally Posted by Hotspur

The one in the back to lock the breech block?

Cheers

GC

As i approached in post #6.
To my unexperienced eye, the hole in the back seems to be horizontal.
I reckon i see various holes but only one touch hole.
Also the breech cavity doesn't seem to accomodate a classic rotating cilindrical re(chamber), but rather a squared frame for a lid.
There ought to be an explanation for such an atypical system.

.

[Matchlock]

Exactly, 'Nando,

The hole in the muzzle plate/flat is highly unusual and dangerous, and the lateral damages seem to be rests of former integral stone trunnions, which would make much more sense than drilling a horizontal hole for a transversal bar into granite ...

Best,
Michl

[Matchlock]

With a lot of things said, I'm still facing two severe problems with three seeming recesses in line on the surface; wish I could mark them in red as 'Nando managed to do ...

m

[Andi]

Here is a nice article Lu Mau De - Untersuchung über die Erfindung der Geschütze und des Schießpulvers in China, unfortunately in German language, about the use of early firearms, explosives and cannons in historic chinese literature. There are also pieces mentioned as "Steinkanonen" (stone cannons) but the author did not specify if this are cannons made of stone or cannons for shooting stone balls. But I guess the author means cannons for shooting stone balls.

But the author mentiones lots of other interesting devices like handgonnes with barrels made of bamboo. The Article was published in a periodical Sinica somewhen between 1925 and 1942, unfortunately I was not able yet to sort out the relevant issue.

Many of the holes on the stone cannons are looking like natural cavities in the stone. It is hard to identify touch holes on the fotos.

[Matchlock]

Hi Andi,


I'm sad to say that this article has been outdated long since, for at least 30 years.

Steinbüchsen doubtlessly means pieces of cannon firing stone balls.


Best,
m

[kronckew]

as old as these appear, the 'extra' holes may have been added well after they were no longer used. they are obviously not mounted as they would have been during service, as they are now just propped up on blocks. probably would have had a bit finer surface finish way back then as well. i've seen a sketch of an early breech loader where the breech block was held by a pin thru the centre of the breech with the touch hole forward of the pin hole. the breech block did not contain the charge, just sealed the end. most designs used a wood wedge to tightly force the plug against the breech, and thus has a square section behind the cartridge/breech plug to hold the wedge.

in any case i would likely have preferred being the target than the gunner with that frangible beasty. at least i'd want to be far away when it went off.

only somewhat related, i remember a episode of 'myth busters' where they made a cannon entirely of duck tape that fired an 18 pound ball rather effectively. held up for a few shots if i recall...