INTRODUCTION

What young boy has not wanted a cannon to play with? These ubiquitous memorials in public parks and historic monuments, on board replica barques and brigantines, are redolent of the days of piracy and siege, as fascinating as they are frightening.

"Half a league, half a league, half a league onward.
All in the valley of death rode the Six Hundred...
Cannon to the right of them, cannon to the left of them
Cannon all in front of them, volleyed and thundered..."
- Tennyson
To the adult eye, there is yet more mystery. When, and where was the cannon invented and who was responsible? My extensive researches on this subject are covered fully in my hand gonne page. My primary motive in writing this is to explore the technology of cannon-founding, particular in context of machine technology. These drawings form part of a set of fifty, probably part of a now lost larger series done in the late 18th century at the Royal Brass Foundry at Woolwich, England. My particular focus here are the drawings depicting the machine shop, which at the time, were considered "top secret". The question of authorship is a complicated one, but they are traditionally attributed to Pieter Verbruggen, son of the Master Founder Jan Verbruggen. Jan Verbruggen was born in 1712 in Enkhuizen, West Friesland. Initially trained as an artist and architect, in 1746 he was appointed as Master Founder for the Admiralty of West Friesland. He had married in 1734 and his son Pieter was born the following year. In 1747, the Dutch Ordnance decided to adopt the procedure of casting cannon solid, and then machine the bore out from scratch. The previous system of casting around a core slightly smaller than the desired calibre, while time-honoured, occasionally lead to disastrous failures. This innovation was credited to Johann Maritz, Master Founder at Burgdorf, Switzerland in 1715, and had been investigated by the Dutch in 1725, but rejected because of conservative attitudes and cost. Maritz's sons introduced the technique to France and Spain, and by the 1730s, the first horizontal boring equipment had replaced cumbersome vertical boring rigs at the armoury at Douai, France. From 1751-1754, the Hague foundry was in crisis because of neglect in infrastructure and difficulty in adapting to the new techniques. Jan Verbruggen was recommended and appointed as Master Founder, and with the help of the ambitious Johan Siegler, (newly arrived from Douai and with 15 years experience) had constructed his first combination boring machine and finishing lathe between 1755-1758. It was at this time that Pieter Verbruggen, newly graduated in law, joined his father at the foundry. While the brilliant new machine solved the machining problems, controversy soon erupted over the suitability of the furnace, designed by Verbruggen's superior, General de Creuznach. While de Creuznach was absent in 1759, Verbruggen rashly demolished the furnace and constructed another to his own design. There is evidence that Siegler (described by his French employer, Master Berenger as an overambitious troublemaker) tried to make the best of the situation, and when sacked for his disloyalty by Verbruggen, threatened to blackmail him. His denunciations led to a 9 year controversy which ended with the Verbruggens decamping to England in 1770. The Woolwich foundry was in an even more parlous state than that of the Hague, due to 60 years of nonstop production and no maintenance. Renovations took almost 4 years, at the end of which guns of an unsurpassed quality were being produced. The eruption of the American war in 1775 lead to an unexpected and frenetic increase of activity, which the foundry was able to handle with few difficulties. Jan Verbruggen died in 1781, and his son in 1786, both master craftsmen and efficient administrators of a vital strategic and industrial resource.
CLICK ON IMAGE FOR A LARGER VIEW IN A SEPARATE WINDOW

"The Furnace Is Tapped"
The pouring was the most critical and most spectacular operation in the manufacture of bronze guns. Centuries of experience, years of training, months of planning, weeks of labour and anxiety went into the preparation. Within minutes, the moulds were filled and the quality of the castings irrevocably decided. It is only natural that guests (seen in the illustration) would have been invited to watch. The pensive figure at the left is traditionally thought to represent Jan Verbruggen.

 
"Chucking"
The cannon has been taken out of its mould, rough-chipped by hand, had the sprue sawn off and been marked with a centre. It is being mounted on the lathe with a block and tackle to have the bearing surface machined on the muzzle preparatory to boring. The rotation was driven by a square protrusion on the breech of the cannon, by a team of horses and gearing in the room next door. The machinist signaled the team driver to start and stop using bells. The turned bearing surface would necessarily be concentric with the centre. This was then carefully mounted in a hardened steel bearing and a pilot hole drilled where the centre hole was.

"Turning And Boring"
A 24 pounder has been completely chucked up and aligned is is being simultaneously bored and turned at slow speed (4 1/2 to 7 rpm) . The square protrusion at the breech and bearing at the muzzle can be clearly seen. At far left is the bell pull to stop and start the horses. The majority of the barrel, which is heavily decorated, will be hand finished, but the turned sections are clearly shown. The turner is using a compound rest, with a chain of articulated covers to protect the leadscrew from swarf. The whole rest was skewed on the floor to turn the tapered sections of the cannon. The colouring , as well as written evidence, indicated that most of the metal parts of the lathe were bronze. The job of drilling a hole in a solid piece of bronze was extremely difficult to achieve with accuracy. The first hole in a piece this size might take up to 12 hours to bore, including time to rest the horses, let the tool cool, and lubricate the drill with tallow. Successively larger drills, or rather boring tools were used to open the bore out to its final diameter and produce a mirror smooth finish. The man in the middle is the master turner, who is supervising the progress of the drill, and the man at the far right advances the drill by steadily turning the large capstan wheel.
"Turning At Night"
This scene may have been drawn during the American war when production was augmented radically and night work became necessary. Hand held turning tools are being used - the compound rest stands unused in the corner. Hand turning was used for the fillets and other concave surfaces. The main purpose of turning was to uncover any casting flaws. This became so important that all decoration was eventually left off cannon. This happened in Holland after Verbruggen's departure, but was not yet the practice in England.
This is the second machine built by the Verbruggens at Woolwich. The aged and cracked timber was recycled from the old vertical boring mill that had been built in 1715 by Sclach. The metal parts were cast from hordes of metal found while cleaning and renovating the site. In addition, during the American war, the Verbruggens installed a third small lathe, brought by them from the Netherlands. Could this have been a prototype of the machine built at the Hague by Verbruggen and Siegler? It is unfortunate that no illustrations exist. This machine was designed specifically for mortars and boring was done on different principles. The boring was achieved ny swinging the end of the special cutting tool in a 90 degree arc, advancing the cut by 1/4 each time. It is not thought that this machine had a compound rest for turning the exterior.

Another view of the same machine. The huge bulk of the mortar being turned is breathtaking for people who haven't seen modern large capacity lathes at work. The fact that this machine is run by horsepower and was built in 1776 should astonish the rest!
While recently visiting the modern "Batavia" on its visit to Sydney, I spotted this cannon in the accompanying exhibition. I had a strange feeling about it and much to my surprise, it was a Verbruggen. And not just that, an uncatalogued one!
This cute little gun is a 2 pounder cast for the Dutch East India company and comes from the Zuiderzeemuseum at Enkhuizen, Jan Verbruggen's home town.
The inscription is barely legible in this shot, but it says: "IAN VERBRUGGEN FECIT ANNO 1746" and carries the famous VOC monogram of the East India company. I couldn't tell whether the cannon was cast solid or around a core... I tried looking down the bore with my mini-maglite and it was full of kids sweets and lolly wrappers! But I can't help thinking that perhaps it was made on Jan's small lathe which he later took to England with him. Jan was a brilliant Enlightenment technician, and it is inconceivable that some details of Maritz and his methods had not reached him by this stage and perhaps interested him enough to try something on a small scale at his own cost - he would have hardly absconded from the Hague in 1770 with equipment of such conspicuousness that belonged to the Dutch Ordnance! This piece is not listed in the preliminary catalogue published by Jackson and de Beer, and appears to be only the tenth piece found that was produced by the Verbruggens pre-Woolwich. My find!
REFERENCES

Jackson and de Beer, "Eighteenth Century Gunfounding", David and Charles, 1973

Please ignore Rolt's section on the Verbruggens in "Tools for the Job" as it is full of inaccuracies! All 50 illustrations and detailed descriptions may be found in the above work.

LINKS

medieval technology - practical experiments in early cannon

cannon ltd. - cannon founders

dixie gun works -cannon retailers

cannon mania


Copyright: Dis Pater Design, 2000

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