How to: Build a replica Cannon Part Two

The Gun Barrel

The core element, the cannon's barrel, is so named because the earliest guns were constructed with iron staves bound securely by hoops as was the case in coopering a cask or barrel. The other key piece is the gun carriage. The challenge for this project is how to build both elements as light as possible but robustly enough to survive the rigours of transportation and repeated use. What follows, in Part Two, is one possible solution for constructing a replica gun barrel, the named parts of which are shown below:

Step One A 110 mm diameter plastic down-pipe, cut to a length of 1220 mm, formed the core of the barrel. The smooth bore was intended to allow loading and dry "firing" drills to be carried out by "gun crews" of schoolchildren. Any object (faux powder charge, faux shot, sponge, rammer, etc.) cannot exceed the internal diameter of 100 mm.

Step Two Typically guns taper along their length being widest at the breach, where the increased mass of bronze or iron acts to contain the overpressure caused by the exploding propellant, and narrower at the muzzle. To create the tapered effect a series of 12mm plywood discs were cut to different diameters, as shown below. Each disc had a 110 mm diameter hole cut so they can be centred along the plastic pipe.

Step Three The "cascabel" or breach endcap was formed from a series of solid plywood discs cut to the diameters (Ø) shown right and glued together. The exception was the first 220 mm Ø disc which had a 110 mm Ø centred hole cut to accept the pipe and securely glue the latter into the breach endcap. A round wooden newel post cap formed the "knob". The whole breach endcap was sanded to produce the appropriate rounded profile.

Step Four Remembering to glue the discs in situ before the endcap, the result created a central barrel with reinforcing ribs as shown below. Note that the tape ensured each rib stayed in place as the glue dried. The next step was to add two horizontal cylindrical protrusions for use as barrel's mounting or pivoting point. These "trunnions" were formed from 65 mm Ø plastic pipe, each being 130 mm long and capped at one end with a wooden disc insert. The opposite end was profiled to fit flush with the larger "barrel" pipe and then glued either side, centrally at the barrel's midpoint.

Step Five With the internal structure completed, the next step was to create the cannon's exterior barrel shape. The original intention was to have an outer shell of fibreglass but, with no previous experience of using fibreglass, it was decided to take a simpler approach, namely papier mâché. A woven adhesive webbing was stapled to the discs to produce a cone onto which layers of papier mâché could be added. The first layer used commercial blue paper towel soaked in a mix of 1:1 PVA glue and water. While this was successful it is not recommended as the paper towels tend to delaminate when very wet and the resulting finish is not as smooth as would have been liked. Subsequent layers used torn strips of newspaper as these will accept the adhesive much better, are more robust but still malleable, and produce a smoother finish. Alternate the layers to form a cross-ply for added strength. From the image above right the internal ribs are still visible creating a "wavy" profile. Building up the layers between the ribs eventually solves this problem and allows a smooth exterior to be created with the final papier mâché strips laid lengthways.

Step Six Given the amount of explosive energy released when fired, cast cannon barrels were reinforced at points along their length with iron bands, known as reinforcing bands or astragal and fillets, as shown in the drawing of the Winchelsea gun below. The next challenge, therefore was to create the bands.

The chosen solution was to encircle and glue in place sash cord over which papier mâché strips were laid to produce the desired effect (below). The over all effect approximates the reinforcing bands typically found on a gun but are not particularly representative of barrel astragal and fillets.

The drawing below provides not only the cannon barrel's dimensions but the approximate position of each reinforcing band:

Step Seven With the barrel reinforcing bands and trunnions finished, a vent or touch-hole was the last addition (see right). A 4mm Ø counter-sunk hole was drilled through a piece of plywood (approx. 100 mm long x 40 mm wide x 5mm thick). The plywood "vent field" was glued between the endcap and the first barrel band and disguised with papier mâché. To allow the use of a "priming iron" to simulate the piercing of the powder charge, the 4 mm drilled hole was extended through the barrel body.

And finally, the complete barrel assembly was finished with coats of matt black spray paint.

Next... With the barrel complete, the next step is make a supporting carriage. So, in Part Three we will explore "How to:" build a lightweight, portable wheeled gun carriage.

Vesuvius Erupts!

While researching the manufacture and use of fish sauce in the ancient world, we came across an article published in 2008 that claimed “Remains of rotten fish entrails have helped establish the precise dating of Pompeii's destruction.”[1]

While researching the manufacture and use of fish sauce in the ancient world, we came across an article published in 2008 that claimed “Remains of rotten fish entrails have helped establish the precise dating of Pompeii's destruction.”[1]
Nearly 2,000 years ago, Mount Vesuvius erupted burying Pompeii and Herculaneum, two ancient Roman towns on the Bay of Naples, in volcanic rock and ash. Covered in between 3 m and 6 m of debris, the existence of these towns was completely forgotten within a few generations. In the 18th-century, however, Pompeii was discovered having lain undisturbed and protected from the elements since AD 79. Extensive excavations soon began, and Pompeii and Herculaneum have given us some of the most precise knowledge of how a Roman city looked and how its inhabitants lived.

In 2008 it was reported that seven jars, unearthed some years before in the house of Aulus Umbricius Scaurus, had had their content analysed. Given that Scarus was Pompeii's most famous fish sauce producer, it should come as no shock that the jars contained Roman garum. Moreover, the desiccated remains found at the bottom of the jars revealed that the last Pompeian garum was made entirely with bogues, a Mediterranean fish species that abounded in the area in the summer months of July and early August.[2]

According to Annamaria Ciarallo, director of Pompeii's Applied Research Laboratory: "Analysis of their contents basically confirmed that Mount Vesuvius most likely erupted on August 24th, AD 79, as reported by the Roman historian Pliny the Younger in his account on the eruption.”

For the last five hundred years, articles about the eruption of Vesuvius have typically agreed that it began on August 24th. Moreover, this date is seemingly confirmed by a 1508 printed version of a letter between Pliny the Younger, an eyewitness to events, and the Roman historian Tacitus, which was written some 25 years after the eruption. The problem, however, is that hand-copying of the original letter before 1508 may have led to the date being corrupted. Manuscript experts believe that the date originally given by Pliny was either August 24th, October 30th, November 1st, or November 23rd[3]; an imprecise set of dates caused by how the Roman calendar was calculated. Regardless, given that the August date had been reproduced in the majority of extant medieval manuscript copies[4] it was accepted by most scholars and incorporated into nearly all books written about Pompeii and Herculaneum for the general public.

Since at least the late 18th-century, a minority among archaeologists and other scientists have suggested that the eruption began after August 24th, during the autumn, perhaps in October or November. Some of the evidence for a later date include:

• In 1797, for example, Carlo Rosini reported that excavations at Pompeii and Herculaneum had uncovered traces of fruits and braziers indicative of an autumn date, not a summer one.

• The remnants of more autumnal fruits (such as pomegranates) were discovered by archaeologists in 1990 and 2001. About the same time, it was reported that the remains of victims of the eruption were noted wearing heavier clothing more appropriate for later in the year. Furthermore, large earthenware storage vessels laden with wine at the time of their burial by Vesuvius implies the eruption occurred after the year's grape harvest and wine making.

• In 2007 a study of prevailing winds in Campania[5] showed that the southeasterly debris pattern of the first-century eruption is quite consistent with an autumn event, but inconsistent with an August date. During June, July, and August, the prevailing high-altitude winds flow to the west meaning the volcanic debris would have been carried in the wrong direction to bury Pompeii.

• Two coins, from early in Emperor Titus' reign (June 24th, AD 79 to September 13th, AD 81), were found in a hoard recovered at Pompeii's House of the Golden Bracelet. Although the coins' minting dates are somewhat in dispute, a numismatic expert at the British Museum, Richard Abdy, concluded that the latest coin in the hoard was minted on or after June 24th (the first date of Titus' reign) and before September 1st, AD 79. Abdy states it is "remarkable that both coins will have taken just two months after minting to enter circulation and reach Pompeii before the disaster."[6]

• In October 2018, Italian archaeologists uncovered a charcoal inscription in new excavations. The scrawled inscription, likely made by a worker renovating a home, is dated 16 days before the "calends" of November in the old Julian calendar. By our modern dating method this becomes October 17th. Given that the inscription is unlikely to be have been a year old in AD 79, it sets the earliest possible date for the eruption.[7]

The signs for an October eruption are stacking up but how to explain the evidence from the garum jars? If the bogues were caught in August, the fermentation process by which fish sauce is made requires several weeks of macerating in the sun. Andrew Dalby states this process would take about two months[8], which fits well with an eruption in October. So, despite Annamaria Ciarallo’s 2008 discovery, the August 24th date is most likely incorrect meaning Pompeii and Herculaneum were probably devastated sometime after October 17th, AD 79.
Notes:

1. Lorenzi, R. (2008), “Fish Sauce Used to Date Pompeii Eruption”, Discovery News, retrieved July 24th, 2020.

2. The eruption froze the sauce right at the moment when the fish was left to macerate. No batches of finished garum were found, since the liquid evaporated in the heat from the eruption.

3. Berry, J. (2013), “The Complete Pompeii”, Thames & Hudson, London, p. 20.

4. There are no surviving Roman copies of Pliny’s letter.

5. Rolandi, G.; Paone, A.; De Lascio, M.; Stefani, G. (2008), "The 79 AD eruption of Somma: the relationship between the date of the eruption and the southeast tephra dispersion", Journal of Volcanology and Geothermal Research, 169 (1), pp. 87-98.

6. Abdy, R. (2013), "The Last Coin in Pompeii: A Re-evaluation of the Coin Hoard from the House of the Golden Bracelet", The Numismatic Chronicle 173, pp. 79-83.

7. BBC News, (2018), "Pompeii's destruction date could be wrong", retrieved July 24th, 2020.

8. Dalby, A. (2003), “Food in the Ancient World from A to Z”, Routledge, London, pp. 156-157