|MadSci Network: Science History|
There are plenty of ways to build a siege engine that look OK but are, to say the least, grossly inefficient even if they are somewhat effective. The mangonel, or onager, torsion machine is much more efficient when used with a sling, and in this configuration is sometimes called a scorpion. In fact any device using a throwing arm, including the human arm (see David and Goliath), will benefit from using a sling. When constructed with a spoon it may look all right but has a greatly reduced range for the same energy input and in my experience becomes more likely to misfire upwards and even backwards. The bent pole with a spoon on the end, the Acme machine Wiley got, is probably the worst way to try to throw things. If you’ve ever tried it you know it suffers from comparatively poor energy storage and, in my opinion, an even greater tendency to misfire.
Did anyone ever try Wiley’s machine in combat anyway? We have no record of it that I’ve seen. Then again we don’t have a very good historical record of quite a few of the devices we’re pretty sure were used either.
For historical references try www.mangonel.com, www.historicalweapons.com, or the article, “The Invention of the Counterweight Trebuchet: A Study in Cultural Diffusion” by Paul E Chevedden which you can probably turn up on the web. Chevedden’s paper is mostly about trebuchets but has copius references and footnotes and does mention torsion machines to some degree.
The mangonel.com site has their take on a petraria which though it may never have actually seen use in ancient or medieval warfare does use a spoon arm. The historicalweapons.com site has a section on prototype siege engines. There you will find a nice looking concept machine by none other than DaVinci called the springauld. It uses the a triply compounded bent lever much like Wiley’s single lever but DaVinci’s machine has a sling release. Like many of DaVinci’s concept drawings it may never have been built for use other than as a curiosity.
Torsion and flexion machines would work well to throw projectiles up to a few tens of pounds over the wall of a city or into massed ranks of soldiers. They do however suffer from a lot of wear and tear in use and even idle they still have highly strained parts. To throw the few hundred pound objects needed to destroy walls became the job of the large gravity powered trebuchets of the medieval period. Most of our experience in the Engineering department here is with the gravity powered trebuchet. They can be very efficient. Our largest will throw a 16Lb ball 200Ft using only 440Lb of counterweight and is fully capable of putting a hole through a standard concrete block wall with a single shot. It has fired hundreds of rounds reliably and with very little maintenance.
For these reasons I doubt the Acme machine poor Wiley got in the mail was ever seriously used even though the Greeks and Romans got a lot more use for a long time from its stouter cousins.
Try the links in the MadSci Library for more information on Science History.