mauricio_agg t1_ir3ulj8 wrote on October 5, 2022 at 3:19 AM

Reply to comment by War_Hymn in Why No Roman Industrial Revolution? by Magister_Xehanort

The French were already in that during the Napoleonic era regarding to cannons.

War_Hymn t1_ir3zz7m wrote on October 5, 2022 at 4:09 AM

Cannons in your specified period were cast as one piece - there's not much machine parts to be fitted or interchanged.

AnaphoricReference t1_irdrqgm wrote on October 7, 2022 at 8:00 AM

Every cannonball needs to fit the barrel as closely as possible to maximize the power of the cannon. This leads to two big technical problems: firstly precision, and secondly metallurgy to keep the cannon from exploding when you achieve the desired tight fit. Precisely the two key problems you need to solve for interchangeable machine parts.

The Japanese successfully fast-tracked themselves for Industrial Revolution with a decades-long program trying to replicate the range of European cannons. And this was with access to European scientific and technical knowledge through the Dutch trading post (Deshima) in Nagasaki. Otherwise it would have been even more difficult.

War_Hymn t1_irf5d1y wrote on October 7, 2022 at 4:31 PM

You have to understand that they were still pretty limited in terms of large scale precision manufacturing back in the early 1800s. The skilled craftsmen of the time could certainly create very tight and precise fitting metal parts as showcased by the accurate timepieces made by 18th century clockmakers, and also Eli Whitney's stunt demonstration of interchangeable parts in a couple of muskets he had made by hand.

But to make precise parts consistently the same, and in great quantities cheaply was a whole different matter and wasn't really achieved until the mid-19th century. Until that time, complex mechanical devices and parts that required minute precision to work had to be made and fitted by hand and eye. Producing true interchangeable parts with this system was not economical. Even Eli Whitney, a pioneer in the field, failed to live up to his claim of producing 10,000 muskets in 2 years, taking 10 years instead. This rate wasn't much better than what the larger gunmaking firms in Birmingham, England (a major center of gun production at the time) were doing in the late 1700s without the aid of a interchangeable parts system.

>Every cannonball needs to fit the barrel as closely as possible to maximize the power of the cannon

Cannonballs of that period were usually casted from casted iron, with no final machining afterwards. Casting does not lend to precise final dimensions as 1. It creates a rough, imperfect finish, and 2. Most metal and alloys tend to shrink in the mold as the casting cools, leading to slight variance to the final dimensions of each casted shot if factors such casting/pouring temperature, composition, cooling rate, etc. are not exactly the same. In addition, rust and grime built up that inevitably occurs during storage/transport, especially on board a damp seagoing ship, would further change the functional dimensions of the casted shot.

So as you see, there had to be some amount of gap or windage between shot and gun bore in Napoleonic-era cannons in order to compensate for these discrepancies. Usually about a few millimeters for naval or artillery guns, or a few percent of bore diameter. In service, the windage grew significantly as each firing eroded the cast iron or bronze barrel (which were much less durable than steel or wrought iron barrels used in later guns).

In comparison, the British Brown Bess musket in that same period fires a .71 cal ball in a .75 cal bore barrel - a windage of about 5% - and it'll still develop a peak internal pressure of around 10,000 psi with the standard military powder loads at the time despite such a "loose" fit. So no, you don't need tenth of a millimeter precision for a Napoleonic cannon, and trying to make one so would had been prohibitedly expensive.

AnaphoricReference t1_iris9zd wrote on October 8, 2022 at 3:02 PM

Interesting detail. For centuries, European ship cannons were perceived to outrange Japanese and Indian cannons because the Europeans were always a step ahead on daring to reduce windage, because of trust in their production processes.

There was a topic half a year ago or something about 'ugly' late Roman coin faces vs. 'pretty' early Roman coin faces. The explanation people settled on was: mass production. Heavy pure gold and silver coins made in one production line for a relatively small upperclass is something else than making thin coins from alloys that don't flow well in many production lines for millions of users. So to keep the coin faces consistent and recognizable you made them simpler. The problem of scaling up production while keeping consistent quality is as old as civilization. And it still is, obviously, in for instance nanolithography.

War_Hymn t1_irjrk6t wrote on October 8, 2022 at 7:49 PM

>European ship cannons were perceived to outrange Japanese and Indian cannons because the Europeans were always a step ahead on daring to reduce windage, because of trust in their production processes.

Their guns probably did have better windage thanks to superior manufacturing (to achieve such boring precision, they literally used a lathe big enough to turn a cast cannon against a boring bar), and better gunpowder too, but being able to create a 1:50 windage to bore ratio cannon tube doesn't automatically spell out to the ability to mass produce interchangeable parts, especially when said parts called for reproducing machined dimensions to a hundredth or thousandth of an inch accuracy, which again something that wasn't worked out until the mid-1800s.

Interesting you bring up Roman coins, because I recently read that the debased "silver" coinage of the late empire (when silver supplies had depleted) were basically just copper coins washed in silver salt to give them a silver coating that was so thin that it rubbed off after moderate use. As the coins had to be stamped after the silver washed, for good reason any stamped impression made on them couldn't be too sharp or deep, lest the silver wash would be damaged and the copper base be exposed, exposing the farce.