From the Trailspike
By Mark Magiera
Shortly after the wonderful event at the Daniel Boone Homestead in May, I received a call from our wonderful Adjutant to the Continental Line. "Mark!" says she, "Would you like to write an article about artillery?" So in this issue, I would like to talk about two topics. "The importance of using cannon grade black powder for your artillery piece", and "How to avoid marching your company in front of a loaded gun".
Firstly, I will spare all of you a long political diatribe about artillery tactics. That honor is for an individual with infinite more knowledge than myself. That's right, despite how I let myself be perceived, I am not the Lord God of Artillery and I'm not married to St. Barbara. I do know which end of a cannon is supposed to belch flame, shot and smoke, though. Over the last few seasons in the service of the Continental Line, and that of my own unit, I have had to crack every book I could get my hands on regarding artillery. From the original Book of Drawings by William Congreve to A Treatise of Such Mathematical Instruments as are Usually Put into a Portable Case... with an Appendix Containing the Descriptions and Use of the Gunners Calipers of John Robertson (whew! say that in a breath). With that said...
Cannon Grade Powder
While reading the Guidelines to Safety and Black Powder Standards of the Continental Line, which I may add are very well written, I noticed that on page 9, there is a table of maximum loads for musket and cannon of various bore. What comes into question is why this chart specifically states the use of Fg to Cannon Grade in the section on artillery.
What's the big deal? Well, black powder is a mixture of potassium nitrate, sulfur and charcoal. When burned, it produces a quantity of gas equal to 280 times the volume of the powder in an unburned statei. The different grades of black powder affect the rate of burn, which in turn affects the amount of pressure in the firing chamber. For example, Fg black powder burns slower that FFFFg. If one were to measure equal amounts by weight of the two, the FFFFg would burn quicker, because there is more surface area to the grain. This quicker burn rate also exponentially increases the amount of PSI that the barrel must endure, regardless of whether we are talking about muskets or cannon; shot or blank.
Case in point? Since the birth of artillery, man has endeavored to understand the chemistry and metallurgy of artillery. At the close of the 18th Century, basic understandings were beginning to be realized and accepted. Still, accidents occurred, especially in heavy ordinance. During an exhibition in 1844, President Tyler's cabinet was nearly wiped out. This prompted the development of reliable data on the subject.
How does one measure the pressures of the burning powder? In 1883, the U.S. Ordinance Department began using a Woodbridge "crusher" gauge, which was inserted into the cannon before it was loaded. This was an improved version of a gauge designed by Thomas Rodman in 1858. Once the gun was charged and fired, the gauge was extracted and a lead or copper slug, which was inside the gauge, was measured for the amount of compression the charge created. In 1971, Matthew Switlik of Michigan conducted a series of tests in order to determine what effects granulation made on breech pressure using this method. His findings were remarkable. Using a three inch ordnance rifle in good condition, the results can be comparable to that of a French three pounder (bore is 3.011 English inchesii). This bore is roughly between that of an English three and six pounder. This test used a 10 lb. projectile.
|Fg sporting||(240,000 grains per pound)||8oz. charge||produced 12,000 P.S.I.|
|FFFg sporting||(2,100,000 grains per pound)||6oz. charge||produced 18,000 P.S.I.iii|
In another test program conducted in 1986-87, a piezo-electric ballistics transducer was used to record time pressure curves for a variety of black powder grades. This method used a probe connected to an oscilloscope. The device bases the characteristics of certain crystals which develop an electrostatic charge when compressed, which is directly proportional to the pressureiv. Peak pressure of each charge was calculated by the curve produced on the instrument. Part of the test compared Fg Sporting Black Powder to Cannon Grade Sporting Black Powder, with results that were equally eye opening. Firing full service charges with service projectiles on a 3 inch ordnance rifle, the Fg powder yielded almost 40% more pressure than that of the Cannon Grade powder. Remarkably, the velocities recorded in both cases were essentially the samev. The numbers are like this:
|Fg Sporting||8 oz. service charge||11 lb, 6 oz shot||produces 19,700 P.S.I.|
|Cannon Grade Sporting||8 oz. service charge||11 lb, 6 oz shot||produces 10,500 P.S.I.|
By using Cannon Grade Sporting Powder made by Goex or the equivalent of that sold by Elephant, we would be protecting the Continental Line from a potential liability. In actuality, it is up to all of us to voluntarily impose such restrictions upon ourselves. We are using original tables of the 18th Century for these artillery pieces. The problem is, we aren't using original powder. Black powder manufacturing today is more scientifically refined than it was 200 years ago. The high volumes and weights of powder to be used for cannon during the 18th Century was due to poor production and storage.
It may be in the best interest of the Continental Line to revise its tables in the future. Although I have never been to a CL event where the opportunity was present to demonstrate, on a controlled range, live fire with projectile, who is to say that in the years to come that opportunity may not present itself? An avenue that possibly could be taken is to firstly, designate the existing tables as "blank fire" loads. Secondly, a projectile table should be drawn up to consist of recommended weights and grain of powder and shot for live fire with projectile demonstration. I know that arguments are to be had, debate is certain to follow regarding such an issue. In the end, it will make the hobby more safe and enjoyable for all of us.
Avoiding Friendly Fire
At re-enactment events, we are witnessing a resurgence of artillery companies falling out as battalion guns and not as battery guns. A pleasing sight for hard core artillerists who, for years, saw such a valuable resource wasting away on a ridge or hilltop. Even more pleasing is to see the number of infantry units taking active interest in being placed by these pieces of ordinance. For we need one another in portraying a convincing force for opponent and spectator. During the heat of battle, though, confusion is easy to flourish. With the added smoke, watching the opposing forces and attempting to keep in time to the script, mistakes can be made. Luckily, the majority of us have heads on our shoulders and know the difference between time to move and time to be safe. Every once and a while, the artillery is put into a squeeze, when an officer decides to advance his unit and the line skews in front of a loaded artillery piece.
The reaction of the entire artillery crew is that which, of course, draws embarrassing attention upon itself. Even more embarrassing is when the company must about face and march back to a safe position. This is due to the fact that the artillery doesn't have the luxury of shouldering its arms. So, folks, what do we need here?
It comes down to a few things, firstly, communication between battalion commanders and companies, as well as between companies, must be improved. If an artillery piece is positioned on line between companies, it is up to the officers of both artillery and infantry to keep verbal and visual contact with each other during the show. Let the sergeants keep the men dressed and the guns loaded.
Secondly, slow down if you have artillery. the battle is just as enjoyable by taking your time than it is running around like a bunch of banshees. Quite often, I listen to the cadence and time it to discover infantry moving at 100-110 beats per minute (bpm). Ideally, the 18th Century Common Time for a march or even battle is an average 82 bpm. At best, we can keep up at 90 bpm, which is a casual walk for an unimpeded individual. Additionally, the majority of infantry I know complain if they don't shoot at least a full block for a show, so stretch out the scenario.
Thirdly, take the opportunity in the future to go to an event with an artillery crew. There are a number of units up and down the coast that are more than willing to put you through the motions and experience a different high. At Monmouth, the Chairman of the CL fell out as artillery and not surprisingly, came away with a new and positive view on artillery. Everything we do is a learning experience.
There are some easy guidelines to go by if artillery is placed by an infantry unit:
- Find out who's the commander of the gun.
- Keep your troops 5 to 10 paces behind the muzzle of the cannon or they'll get what is called cannonear's. (Sure sign: officers who lose their voice halfway into a show.)
- Battalion Commanders, let the artillery know of the advance first.
- On a bayonet charge, the artillery stays put in the case that if the charge fails, there is a rallying point for the infantry.
There are easy guidelines for the artillery, too:
- Bring the gun on line placed 12 paces to the front of the battalion, with 15 paces between the guns and the infantry on either side of the gun.
- Once the gun is loaded, fire it right away. Then, immediately secure the vent, worm and sponge. It makes moving more efficient.
- If an opposing force crosses the minimum safe distance of 150 feetvi, have the crew cross the rammer with the wadhook to make an X above the barrel. See figure 1.
- Same goes if it's friendly forces.
- While the infantry conducts a bayonet charge, secure the gun and be ready to load if the charge fails.
This extremely small list doesn't even begin to brush the intricacies of artillery. But it's a beginning to what I would hope would be a future of articles by other authors in the Continental Soldier on artillery. Every year, the CL is getting bigger and bigger, with size comes the need for more organization to make these gatherings fun for all.
Until then, I remain, you Obt Svt.
iAdrian B. Caruana, The Pocket Artillerist (Jean Boudriot Publications, Rotherfield, 1992) Pg. 17.
iiJohn Muller, A Treatise of Artillery, 1780 (Museum Restoration Service, Bloomfield, Ontario, 1977) Pg. 10.
iiiMatthew C. Switlik, Report on the Conduct of Breech Pressure Tests (Three Rivers, Michigan, 1971).
ivMatthew C. Switlik, "Blackpowder Load Tests", The Artilleryman, Vol. 9, No. 4 (Cutter & Locke, Inc., Arlington, MA, 1988) Pg. 8.
vMatthew C. Switlik, "Blackpowder Load Tests", The Artilleryman, Vol. 9, No. 4 (Cutter & Locke, Inc., Arlington, MA, 1988) Pg. 13.
viThe Continental Line, Guidelines to Safety and Black Powder Standards, (The Continental Line, Inc., 1990) Pg. 5.
Copyright © 1995 Mark Magiera. All rights reserved.