New techniques for understanding 17th century siege warfare

 

Reconstructing the maximum possible diameter of a spherical bullet using the bowl of an impact scar from St Luke’s church, Holmes Chapel (image: Dr Paul Bills, University of Huddersfield).

I came across this 4-year old article on the English Civil War. It's interesting, though a bit technical.

New archaeological techniques, however, are beginning to provide more scientific explanations of how 17^th century warfare was fought. In this guest post Amanda Wynne from the University of Huddersfield explains how laser scanning technology is helping us to more accurately interpret English Civil War sieges - and the benefits the results may have for other fields ...

I wish they had included a scale with this picture. But based on my estimate of a Nikon lens cap, that is a damn big scar on this chunk of sandstone.

 Experimentally produced bullet impact scar from a 12 bore musket ball.

So how big is a 12 bore musket ball?

Well 12 bore means that 12 lead balls the diameter of the barrel would weigh 1 pound. So 1 musket ball weighs 1.33 ounces. For those of you from the post Napoleonic world, that's 37.8 grams. You don't want to get hit with that even if the muzzle velocity is only 400m/sec.

The article on Gauge (bore diamater) in Wikipedia gives provides formula to calculate the diameter of the ball. 

• Divide 453.59 (grams in 1 pound avoirdupois) by n to find the mass of each one of the balls.
• Divide it by 11.34 (density of lead) to find the volume of the ball.
• Multiply it by 0.75 and divide it by pi, then find its cube root, (rearranged from the volume-of-a-sphere equation) to find its radius in cm.
• Multiply it by 2 to find the diameter in cm.
• Divide it by 2.54 to find the diameter in inches.

Crunching the numbers yields a diameter of 4 cm or nearly 1.6 inches! They certainly had big balls back in the day.

${\displaystyle d_{n}=1.67051437/{\sqrt[{3}]{n}}}$

Units of Measure

Currently I'm reading a translation of Arturo Pérez-Reverte's book The Siege. He's the author of the very good Alatriste series that I mentioned in a previous post. This isn't a book review so that is all by way of preamble. In beginning of The Siege there is a List of Currency, Weights, and Measurements which includes the toise, "an Old French measurement equivalent to about 6 feet." The term sounded vaguely familiar which piqued my interest. So I looked it up and learned that, the toise is about six pieds (a pied in the old English measure (the kind we Americans still use) or about 2 meters. 

Which is perfect for use in a game since it is (a) authentic and (b) close to something already familiar to the players, e.g. feet for the USA and meters for the other folks.

Here's a table of ancien France linear measures from the article, Units of measurement in France before the French Revolution.

Unit	Relative value	SI value	Imperial value	Notes
point	1/123	~0.188 mm	~7.401 thou	This unit is usually called the Truchet point in English.
ligne	1/122	~2.256 mm	~88.81 thou	This corresponds to the line, a traditional English unit.
pouce	1/12	~27.07 mm	~1.066 in	This corresponds to the inch, a traditional English unit.
pied du roi	1	~32.48 cm	~1.066 ft	Commonly abbreviated to 'Pied', this corresponds to the foot, a traditional English unit. Known in English as the Paris foot (properly a separate, shorter unit), the royal foot, or French foot.
toise	6	~1.949 m	~6.394 ft, or ~2.131 yd	This corresponds to the fathom, a traditional English unit. Unlike the fathom, it was used in both land and sea contexts.
(league) lieue ancienne		~3.248 km	~2.018 mi	This is an old French league, defined as 10,000 (a myriad) feet. It was the official league in parts of France until 1674.

So I can use authentic measures: pouce, pied, toise, and lieue or switch to their English or metric equivalents, e.g. inches, feet, and miles.

Now I just need to remember that a French league is only 2 miles.