screw threads / gas leakage
 

Today's engineers and production managers can still marvel at this two-piece design connected by reasonably precise male and female threads, fabricated on a ponderous scale in a pre-mechanized age several centuries past.

I also wonder about the design of the apparatus built by the Ottomans to assemble these guns, and dismantle them as needed. The 1868 effort in Britain undoubtedly utilized the best resources of Victorian-era engineering and manufacturing, but that would be stacking the Industrial Revolution against medieval technology.

Pipe wrenches... yes, Nando, probably not :) however the underlying principles still involve leverage and rotational movement, generating enouth torque. The rows of circumferential lug-recesses, and very substantial ones at that in thick mouldings dedicated to the purpose, show us that Orban and his Turkish students had thought things out carefully. Barring the discovery of an illustrated Otto treatise on the manufacture, care, and feeding of these monsters, perhaps we can get an idea of what sort of mechanism was used from ancient texts dealing with mechanical subjects, by notables such as Archimedes, Vitruvius, et al. We do know that Islamic scholars of the Middle Ages were avid students of classical works on mathematics and the sciences.

Now, to your question of leakage of combustion gases from the joint. It would depend, I suppose, on how precise and tight those threads actually were. After all, in use the two components would be tightly screwed together much like the breechplug to the barrel of any muzzle loading pistol or shoulder gun. In other words, a "fixed breech". There shouldn't be any leaking of gases if the threading is suitably tight (ignoring for now the inevitable and small loss of pressure via the vent or touchhole).

Looking forward to other breech designs and how designers coped with gas leakage, it seems to me that this became a problem with breech-loading systems, which involved either a removable chamber-piece (the Portuguese berço cannon and its north European and Oriental equivalents being an example) , or a breechblock that pivoted, rotated, or slid in any number of directions depending on the system (Lorenzoni, Hall, Westley-Richards, Dreyse, Chassepot, ad infinitum) This is because with any movable-breech system, explosive gases will trump the best manufacturing tolerances.

Engineers kept trying different workarounds -- the Prussian Dreyse bolt action needle-fire gun (so named for its slender extended firing pin that pierced a paper cartridge to hit the primer) was a notorious gas leaker but its designers provided a chamfer to the barrel stub that fitted a rebated bolt face that directed most of the gas and particulate matter away from the shooter's face -- at least if there wasn't a headwind. The Frenchman Chassepot improved this greatly by designing his bolt action with an obdurator seal on the bolt head, made of a rubber like substance.. Worked like a charm but the gasket had to be replaced after so-many shots and a soldier's kit contained a special spanner and a packet of spares.
Early breech loading cannon with interrupted-screw hinged breech units would leak gas because the threads were interrupted to allow the opening of the breech and these channels negated the sealing action of screw threads (see above). Believe it or not, this principle was explored by several inventors way before the 19th cent. Discovery of rubber and like substances in the industrial age allowed the breeches to be fitted with obdurator seals analogous in function to the bolt gasket on the French needle-fire guns, and voilà , the result was quite functional.

The magic pill that cured gas leakage was the perfection of the metallic cartridge case, which contained projectile, propellant, and primer in a single, fixed unit. On firing, the explosion expanded the case enough to seal the breech effectively, and the inherent sturdiness of this "fixed ammunition" made for all sorts of possibilities in the way of repeating-fire arms, and ultimately those capable of fully-automatic rapid fire.

Filipe, what a treatise !!!
Definitely your luggage of these things scares me off discussion.
Still, the only experience i have in this particular, is an article (where i was most kindly appointed co-author) on the Westley-Richards (Monkey tail) pistols, of which i had a couple at the time; a version that ended up being only produced for a Portuguese contract (1000 units). Incidentally their failure to be accepted by the British Board of Ordnance was not a gas leakage issue, described the Board as "absolutely gas tight", but their non military advantage.
Back to early artillery, i dare realize that those Orban/Munir Ali guys were smart enough to circumvent problematic solutions like those applied to Berços, for one ( direct plug into barrel and quarter turn rotation), or any other pivoting systems. A screwing principle; not just a quarter or half turn method but, the whole of four threads rotation. This prevented their minds to predict the advent of the gasket or the washer. And adding to the fact, according to the Brits that, the threads were impeccable, i wander if even Lucifer could escape through them. This still not excluding some lubricating/sealing resource, like organic grease.


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screw breeches and monkey tails
 

Obrigado, Nando, pela reintrodução ao sistema retrocarga "rabo da macaque".

Quite an interesting system since it was apparently self-lubricating.

Back to the screw breeches of the Orban cannon -- you mentioned some organic grease as possibly having utility as a backup sealant if the threads were not fitted tightly enough. I'm thinking, in such eventuality, the natural tendency of black powder to form all that dense residue during combustion would have served the purpose quite well since it would have built up during successive shots without the breech being opened each time.

The observations made by the British, and the Greek expert you mentioned, about the quality of fit of these screw threads (as pertaining to the so-called Dardanelles gun) is still an amazing thing. Considering the era in which it was made and the nature of measuring tools and fabrication processes at the time.

And especially when you compare these achievements with the Portuguese introduction of their methods of gun making to Asia. The armory at Goa improved greatly on the basic processes in use at the time, and brought the concept of threaded breech plugs for musket barrels to the Orient. However, as historical literature and surviving guns show, Asian cultures did not take naturally to the turning of screw threads despite their skill in other aspects of metal craft.

It was a difficult lesson. In Iran, the Persian gunsmiths did not even trust the method (maybe to hide their lack of motivation to master the skill?) and through the 17th cent. preferred to use forged-in-place plugs (often anchored with a cross pin), saying it was stronger. The Japanese were almost allergic to screws, they used similar means to seal their barrels and even avoided all screws in constructing their gun locks, which were made all of brass to better suit the assembly methods they preferred (same for the Malays). A scholar writing a PhD thesis on the introduction of guns to Korea shared a Japanese text with me, describing the earliest attempts to cut threads in iron in that country -- the craftsmen tried to use chisels to shape the spiral, which was doable but far from ideal for male threads but virtually impossible for the female threads.

Indian and Chinese artisans eventually got somewhat comfortable with screw threading thanks to repeated experience with European technicians, but when it came to firearms, the tendency to avoid it was still apparent into the 19th cent. Very few Indian toredors or matchlock muskets use anything other than pins or rivets to secure their parts.

So we have to give those 15th cent. Turks A LOT OF CREDIT.

from "wizards" to technicians
 

Yes, Nando, it's true that the first gunners were looked at with a mixture of awe and fear, for having this powerful and frightening thing in their hands, whose noise, fire, and sulphurous stench suggested ties to the Devil. But it wasn't long before modern science began to take over and thus we see the huge advances in artillery design and practice during the 16th cent. all over Europe. We must look to Renaissance Italy as the starting point:

1. Metallurgy and metal fabrication -- Vanoccio Biringuccio's Pirotecnica (1540) is a lucid and detailed compendium of 10 books, over 400 pages' worth in a modern English translation, of the state of the art as of the first half of the century. Book VI, of 10 chapters, covers gun- and bell-founding with tables of standard sizes and weights, and Book VII covers furnaces and molds, and also the making of cannon-balls and the designs of cannon carriages. The author (born 1480) who devoted his adult life to working in the metals industry, including the casting of large cannon. This book is a landmark in technical writing, standing out for its just-the-facts prose, avoiding the inclusion of lore and superstition, as well as flowery allusions to classical mythology, which characterised the literature of the era. The work has seen several editions through the centuries, including partial translations into other languages including Latin and Spanish.

2, Mathematics: Gunners had to do more than just be able to count. During the first half of the 16th cent., the practice became more science than art with the development of powerful tools created by the Venetian mathematician Niccolò Fontana "il Tartaglia" (his nickname The Stammerer came from a speech impediment caused when a French soldier cut his head with a sword when as a kid he had the misfortune of being in a war zone). Tartaglia revolutionized the study of ballistics when he, an avid student of the Greek thinkers, was able to prove mathematically that a projectile traveled in a parabolic trajectory. Not, as Aristotle posited, going straight through the air and then dropping abruptly to earth when its inertia was spent and gravity took over. From this, he was able to calculate the correlation of projectile range to barrel elevation, all else being equal. The figures were compiled into books of tables which became must-have field references for gunners all over the Western world and were disseminated to Eastern armies whose artillery corps were coached by mercenary trainers from Portugal and elsewhere. Tartaglia's studies were also the bases for the invention of several devices for the accurate aiming of cannon, the most important being the gunner's quadrant, which had a service life of over 3 centuries, and which is depicted in military manuals and art from as far away as India and China.

They also made use of wedges, and with spare pre-loaded breeches, could maintain a certain amount of rapid fire. I imagine they were rather unpleasant to stand next to as they must have been fairly leaky when fired.

Irritating computer generated voice: https://www.youtube.com/watch?v=yRGCSSeBatI

So Filipe, it makes sense that, in a coincidental period and as i quoted above General J. Manuel Cordeiro in his "Apontamentos para a História da Artilheria Portugueza – 1895", gunners in North Africa were already familiar with the quadrant, besides other abilities.
At this point a parentheses should be open to remind that, in this ongoing period gunners, as well as foundrymen, were increasingly required in a number far greater than what the nation could provide, for the need to import them from other countries was obligatory. There were highly qualified Germans, Flemish and others. At a certain stage Germans had a brotherhood, São Bartolomeu de Lisboa, were thousands of them were inscribed. More than a thousand have fallen in the battle of Alcacer Quibir (1578).


Wayne, You are right in that the cadence of fire was an asset that largely compensated breech loading flaws.
... And mind you, whatever collateral issues could arise from an 'ancestral' berço like the one in that tube clip, may not be compared with later ones in bronze, improved during evolution imposed by King Dom Manuel, where materials and metallurgic accuracy would achieve a better plug sealing. Also there was no need to stand by the gun side. The one gunner stood safely behind it, at a distance provided by the gun aiming 'tail' (tiller).
On another hand it appears that, the guy shooting the various loaded breeches in that clip, introduces the (simulated) projectiles into the vases, which is a recurrent false case. They are instead stuck into the barrel chamber. All that the breech takes is a gunpowder load ...eventually sealed with wax.

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The Germanic connection
 

Of course, Nando, and not only in the case of artillery but small arms too. As a certain Luso-German arms expert of our time and your acquaintance has pointed out in a book he wrote, the musket with snapping matchlock that reached mature form in Goa as the Indo-Portuguese espingarda was a concept originating in the German lands, most probably Bohemia or Bavaria. Portuguese and Indian artisans improved on what began as a fairly crude device to create the most long-lived and widely used of all matchlock types.

As early as the reign of Dom Manuel "o Venturoso", there was an influential German expat business community in Lisbon, involved in trading valuable commodities between Portugal and northern Europe. A German with some artistic talent made rough sketches of a rhinoceros in Dom Manuel's private zoo which might have been forgotten in the dust of history had not... the King wanted to give the animal to Pope Leo X (following up on a previous gift of a baby elephant), but the boat sank off the Italian coast and it drowned. The drawings ended up in Bavaria, where the famed print-maker Albrecht Dürer used them as the basis for his slightly fanciful but still impressive woodcut "Rhinocerus" dated 1515 -- an image that appears on things like T-shirts and coffee mugs even today.

Also, consider Spain. The Marcuarte lineage of gunsmiths descended from Bartholme Marquardt of Augsburg. His sons Siegmund (Simón) and Peter became established in Madrid in the second half of the 16th cent., and the earliest existing signed patilla miquelet locks are attributable to Simón the Younger, ca. 1625. Is there any coincidence that the action of the patilla mainspring (pushing upwards on the heel of the cock's "foot"), and the operation of a sear moving horizontally through an aperture in the lockplate, are exactly analogous to what we see on the Bohemian snap matchlocks of the 1470s that were sold to Portugal in large numbers during the Age of Discoveries?

It is probably superfluous to cite another example of an immigrant German gunsmith who made an excellent name for himself south of the Pyrenees -- Nicolás Bamproyssen y Bis.

Oh, you mention Flemish. I may be repeating something you know very well, that a sizeable part of the population of the Azores claims those roots. It's evident in the appearance of those Terceirense, Jorgense, and Michelense folks who maintain their distinct communities here in California. Tall people with fair skin and hair, with a variety of surnames like Dutra, Bettencourt, Laranjo (L'Orange), Abreu (Evreux). Silveira (Van der Hagen), etc. Also the little capelas attached to their Irmandade do Espírito Santo halls are so often built in the "gingerbread" style that we associate with the Netherlands and adjoining parts of Germany and Belgium. But I digress... down yet another rabbit hole.

Another big one is the ZamZamma in Lahore.
https://en.wikipedia.org/wiki/Zamzama
Regards
Richard

The issue was quality ...
 

As it appears Filipe, it was pondered that, a better idea was to bring the (artillery) specialists over to the country, managing with them a vital interaction towards skilled production, instead of buying the guns in the international market, exposed to quality imponderables and no specific author to blame.
Afonso de Albuquerque has often made mention to his German gunners good services. Dom Lourenço de Almeida (India Vice-Roy's son) lost and was killed in the battle of Chaul (1508) for, together with other nobles, not accepting his gunner master (Condestável), a highly competent German, the suggestion to position the ships in a determined manner, so that he would take down the enemy's fleet before night fall. This refusal being justified by the fact that, gunning down the enemy's ships would make them assume the Portuguese were not courageous enough to beat them on a face to face boarding. So much for Dom Lourenço's fate :shrug:.


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Good catch, Richard;that's quite a big one indeed.
Yet you could browse on an even bigger thing, the Bijapur Malik-E-Maidan. Its specs are impressive; not so lengthy with 4,5 mts but, with a 55 tons weight, 1,5 mt diameter and a 700 millimeters bore.

Concerning guns with inscriptions, like the ZAMZAMMA, i can not go without showing the TIRO DE DIU, so called due to its use in the First Siege of Diu in 1538.This basilisk was cast in bronze in 1533 during the reign of Sultan Bahadur Shah of Gujarat
It cast in one solid piece and has no ornaments whatsoever except for some laudatory Arabic inscriptions that can be roughly translated as follows:

From our Lord the Sultan of Sultans of all ages; life-giver of the tradition of the Prophet of the Merciful God; the one that fights for the exaltation of the precepts of the Koran; the destroyer of the arguments of the supporters of wickedness; the one that casts away the houses of worshipers of idols; the Victor of the day when the two armies will meet; heir to the kingdom of Solomon; the one who trusts in the God the Benefactor; the possessor of all the virtues – Bahadur-Shah.

After the defeat of the Muslim forces, the gun was sent to Lisbon to serve defense purposes. Later in 18th century it was sent to the Arsenal in Lisbon to be melted so that the metal could be used to cast a statue of king D. José I. However, a religious scholar noticed and translated the Arabic inscriptions on the gun and, once discovering the historical value of the piece, the gun was spared.
This non wheeled beast weighs 20 tons, measures 6,12 mts (5,90 mts core) with 91 cm width (incl. trunnions) and 24 cm caliber.

It is now on display on the Cannon yard at the Military Museum of Lisbon.


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Boring ...
 

I should ask for tolerance over approaching once more the tremendous ambiance that surrounds a combat of artillery; but i could not resist to quote the great historian and grammarian João de Barros (1496-1570), describing the (unsuccessful) attempt, by Nuno da Cunha, to take over the fortification of Diu in 1531 (India). Tolerance also requested for not being able to translate (interpreter) his fascinating words in the exact sense.

" Given as a signal from the skiff of by D.Vasco de Lima, a volley with a piece (cannon) that ours call espalhafato (fuss), due to being very furious, started the sea, the land and the air shaking and changing their quietness; because the sea boiled, its waters jumping over with the falling of volleys which came from town and the boats, where there was great number of musketry, in a way that the shots were like rain, and in the water and the air they met. The land was all put to dust, raised by our shots at beating the fortification. The air was a smoke of sulphur so dark and thick that asphyxiated men, and blinded them, and from it some sparks of fire, that looked like coming from hell. All was a darkness without any light, only a terror, an astonishment to the eyes, torment to their ears and a confusion of cheer, the men not knowing where they were and whether was a dream what they were seeing, or truth ".

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