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Wood Saws

A recent image of a reconstructed medieval dwelling had posts with square cut ends. The wood craft looked rustic and basic but I wondered about those cut ends. They would be easily done now-a-days with a chainsaw but would (no pun intended) there be any saws from the middle ages that could produce a log with square cut ends?

Found a great reference by P. d’ A. Jones and E. N. Simons: http://goo.gl/KClVt2

The first saws were likely knapped serrated edges of a long narrow piece of flint or obsidian. An improvement could have been made by mounting (with hoof glue) the obsidian into a wooden frame. From there, individual pieces of flint/obsidian may have been glued in a line along the wood frame.

Copper and bronze knifes existed several millennia BC. Dings in the cutting edge may have been found to be useful for digging into wood or stone. This eventually evolved into a whole series of dings, forming the first sawblade.

Bronze saws gave way to iron. And development languished for centuries until the carbon could be controlled. Probably the introduction of crucible steel (see previous post) allowed the cutting teeth to be formed from high carbon (hard) steel.

At this point, the “raking” of the teeth developed.

Teeth raked to cut on pull stroke

The saws were probably raked to only cut in only one direction (ie. a common pruning saw) as opposed to both directions (a crosscut logger’s saw), since the iron/steel was too soft for cut in a “push” direction.

Saw teeth raked to cut on both pull and push strokes

Another development during the Iron Age (500 BC to 50 AD) was the frame saw, which kept the cutting blade under tension so it can be used in both directions (assuming it’s raked in both directions).

Modern frame saw

According to Jones and Simons, it wasn’t until the 13th century that tapered blades and set teeth were widely used (although set teeth were used by the Romans). The “set” teeth were bent to the side, in an alternative manner, to increase the width of the cut and allowing the removal of cut debris/powder.

Edge view of set teeth

In modern times, the quality of steel has given us hand saws of every conceivable size and shape.

So, did medieval dwellings have posts with squared off ends? Probably not, the quality of steel required probably too expensive for most medieval peoples.

Thatched Roof

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So I’m writing away (or trying to) in my alternative version of 11th century Ireland., when my characters had to thatch a shelter. Yikes, so how does one thatch a roof?

Note the straw/reeds are cut side down. Ahh…the aluminum ladder may be a bit difficult to find in 11th century Ireland…

Material:
A common reed (phragmites communes) is one typical plant used for thatching. Also wheat straw is used but care must be taken not to damage the straw during threshing (removing the grain from the stalk).
See: http://www.reed-thatching.com/thatch-types.htm

Modern construction:
Was surprised to find that the bottom (thicker) end of the reed is placed “downhill”.
See: http://www.youtube.com/watch?v=qtcaWfsLR0k
See: http://goo.gl/BpcNNS

And when you get done, you can trim the roof:
See: http://goo.gl/GCx4mB

Brain Tanning

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Ain’t got enough brains to tan his own hide.

Ever hear that saying? Well, it is becoming a little dated. Not too many people tan hides now-a-days.

But prior to the industrial age, clothing was not cheap. If one had access to fibers, plant or animal, one could spend days/weeks manually spinning enough yarn from which to weave a piece of cloth. Only then could one actually make clothing.

So for many, the only real options were animal skins (or running around naked).

Even so, turning animal skins into wearable leather (with or without the hair) was an arduous process, taking several days. (But still quicker than spinning and weaving).

The rough steps:

1. Kill something (hopefully with enough brains to tan its own hide…which, in the animal kingdom, is true…not sure about some humans).

2. Scrape the hide of fat and remaining meat on the inside. For the outer part of the hie, one has to make a decision: keep or remove the hair. For a sleeping hide or winter cloak, it would be best to keep the hair on. This does make the process more difficult.

Scraping can be done with sharp-edged stones, antlers, bone, or metal (if available). Two methods of supporting the hide: stake out on the ground. Or tying up on a frame (if wood was available).

Stretching frame for tanning hides

Removal of hair could be made easier if soaked in mildly acidic (urine) or alkaline (wood ash) solutions. In any case, it would be a lot of work and one had to be careful not to cut the hide.

3. Brain treatment. The brains are boiled and then mashed up and vigorously rubbed into the hide (both sides if hair removed, otherwise only the non-hair side).

4. Stretching. This softens the hide. This actually starts while the hide is stretched on the frame (less so is staked on the ground). The pressure while scraping starts this process.

Even while on the stretcher (after de-hairing and brain rubbing), one can use a thick blunt (and smooth!) stick to push against the hide. This does some stretching and for the hide with hair still attached, this may be sufficient.

For a soft hide, one can repeatedly pull the brain-soaked hide back and forth over a smooth, de-barked tree branch or log, turning the hide to stretch all parts.

5. Smoking. To keep the hike soft even when wet, one can smoke (not cook!) the hike. One common method is to tie the hide into a cone or tube and suspend over wood-chip covered embers. One would have to reverse the hide to smoke both sides. The smokey residue is the desired result. Obviously, one would need to monitor the smokey embers to avoid a flare up of flames and the loss of ones several days work.

The chemistry escapes me. For those with knowledge of what the brains (with their oils) does to the hide (made up of collagen, a fibrous protein), please comment with some chemistry!

Some references:

Basic brain-tanning:
http://amohkali.com/files/tancourse.pdf
http://www.native-art-in-canada.com/tanninghides.html

Tanning chemistry:
http://www.conservation-wiki.com/wiki/Books_Section_4_-_Material_-_Chapter_1._Animal_Skin/Leather

Industrial tanning chemistry:
http://nzic.org.nz/ChemProcesses/animal/5C.pdf

Historic Ironworking

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One possible set of developmental steps in the the use of iron.

If one is writing (alternative/)historical fiction, it’s important to get the technology developed in a believable sequence. Iron is a highly technical product and deserves attention in any fiction.

Iron ore is a chemical compound of iron (Fe), oxygen (O) plus impurities.

Bloomery

In this earliest step, air is forced through a mixture of iron ore and charcoal (think of the poor apprentice working a bellows for hours on end). One of the byproducts of the burning charcoal is carbon dioxide which reduces the iron oxide to iron. Typical bloomeries do not reach a hot enough temperature (only 1000 degrees or so) to actually melt the elemental iron. Hence it ends up as a spongy mass called a bloom. The pores of this bloom is filled with ash and slag. Pretty useless until it is reheated and repeatedly beaten to join the iron particles and force out the slag and ash. The result is called *wrought iron*. It was a very labor intensive process. But the early ironworkers probably developed a nice set of muscles.

Carburization

Wrought iron was fairly malleable (soft) metal. Heating in contact with carbon (charcoal again) allowed carbon to migrate into the outer layer of the metal. Quenching in water (or oil…think more carbon) froze the carbon in that outer layer. Now one can get a hard out layer (especially a cutting edge) with a softer inner core (producing a less brittle tool or weapon).

Crucible Steel

The wrought iron, even if carburized, is still soft. If a mixture of wrought iron, charcoal and glass is encased in a clay crucible and heated, the carbon migrates into the iron and the glass forms a protective slag.

Cast Iron

If the iron can be mixed with a lot of carbon and heated to 1140 degrees, the iron is liquid and can be poured into molds. The high carbon content however makes the iron brittle.

Slaves, Warriors and Connections

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Writing anything to do with history forces one to study the past. Unfortunately, this means studying both the achievements of mankind and its grimmer, less savory activities. This last, especially when viewed from modern sensibilities, can be disheartening.

Slavery was a concept I just could not get my head around, let alone put into a fictional adventure. The logistics alone baffled me: how could one force another to do one’s bidding. Why didn’t the enslaved just run away?

I turned to “Slaves and Warriors in Medieval Britain and Ireland” by Dr. David Wyatt (Cardiff University History Department) for a possible answer.

The essence of Dr. Wyatt’s book is given in its abstract: “The purpose of this monograph is to highlight the extreme social and cultural significance of slavery for those societies. The analysis does not focus upon economic conditions or even, necessarily, upon the plight of the slave. Rather, it concentrates upon the lifestyle, attitudes and motivations of the slave-holders and the slave-raiders in these warrior-centered communities. Through the employment of comparative anthropological perspectives this study explores the violent activities and behavioral codes of Britain’s war bands and illustrates the importance of slave raiding/holding for the establishment of power, identity and notions of manhood. In particular, it highlights how the rape, abduction and enslavement of women constituted powerfully symbolic acts for societies which equated prowess, prestige and honor very much with female protection and guardianship. Indeed, one problematic result of the continuing focus on medieval slavery as a means of economic production is that this has ensured an unhelpfully narrow research focus concentrating on male slaves involved in agricultural production. Yet, the majority of slaves in the medieval period would, most likely, have been females living and toiling in the domestic sphere and this is highly significant. Furthermore, this book highlights, more generally, how the dichotomy between slavery and freedom was fundamentally important for defining social hierarchy within the medieval communities of England, Ireland, Scotland and Wales.”

This is heavy stuff. My take-away as far a writing fiction for such an age is as follows:

This stage of society is defined by the family and immediate tribal members. Hostilities over territory, livestock and resources demanded a warrior mentality for Darwinian survival.

Furthermore, protection depended on connections. To survive, allegiances must be made with nearby neighbors (and family members). This formed hierocracy determined by martial skills. Hierocracy also demanded trappings of status, including the power to enslave. Owning slaves thus became a social symbol of power (as well as an economic resources and, in the case of female slave, sexual recreation). Better to travel outside of one’s neighborhood and collect slaves (and booty) to prove one’s prowess in battle than to fight it out for supremacy with one’s neighbors (another Darwinian factor).

This defines the identity of slaves. These peoples fell outside the realm of the allegiances (or social structure) in which one participated. In the context of medieval life (and certainly other times/ages), this meant anyone living beyond one’s narrow world.

To put it more bluntly, anyone outside of one’s connections was subject to enslavement, attack, plunder and murder.

A slave then was in a social situation where all the non-slaves around him/her had connections and/or allegiances to his/her owner. Flight, if successful, would most probably only result in enslavement in another region of different connections/allegiances.

(Travel between “regions” depended on allegiances between high status individuals of different regions. Those granted travel rights would be easily identifiable characters such as messengers, bards, or druids/priests.)

Slavery was a social institution, driven by a warrior culture. And it was connections that defined one’s place in society.

Sulfur and Alternative History

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Gunpowder played a critical role in history of warfare. In European history, it resulted in the decline of importance of mounted and armed Knights as a “commoner” with a matchlock could take out the medieval symbol of wealth and power.

Along with the Knight, the stone castle fell before the onslaught of cannon fire and explosives.

Two factors limited in the development and use of gunpowder. The first concerned the metallurgy required to fabricate the guns and cannon. This will be the subject of a future post.

The second factor was the acquisition of gunpowder components, which consists of a mixture of 75% Saltpetre (Potassium Nitrate), 15% Carbon (charcoal) and 10% Sulfur.

Saltpetre (Potassium Nitrate) can be found in caves, the result of nitrate in the soil being dissolved and percolating downwards to anaerobic soils. There it is converted into ammonium. If caverns are present, it can evaporate at the cave surfaces, where it can be oxidized to potassium nitrate by bacteria (1).

In the absence of the appropriate geology, this process can be artificially produced by letting wood ash and organic material soaked in urine age in a barn or other shelter (2). These sources are limited. But with the event of global trade, Saltpetre could be obtained from India and South America.

The making of charcoal is a well known skill, the only question being the choice of wood. Dogwood, willow and alder are commonly used (2).

Sulfur is an element. This ingredient was probably the limiting factor in the use of gunpowder in European history. Two main historic sources were Sicily and, later by the 14th century, Iceland. The source in each location being volcanic vents.

Of Metallurgy, Charcoal, Saltpetre and Sulfur, it would be hard to control the first three. Sulphur however is extremely localized resource. If a group or state could exert dominion on two relatively small regions of Europe, they could control gunpowder and thus warfare.

An excellent scenario for alternative history would be introducing the technology of metallurgy into pre-gunpowder Middle Ages. Access to one of the sources of sulphur would insure the availability of gunpowder. Exclusive access would insure domination. From there, it’s an adventure story.

1. “Geology and History of Confederate Saltpeter Cave Operations in Western Virginia”, Virginia Minerals, Vol. 47, November 2001, No.4.

2. “The Big Bang: A History of Explosives” by George Ingham Brown, November 1998, Chapter 2 “Making Gunpowder”

3. General reference: http://www.aditnow.co.uk/documents/Krisuvik-Other-Rock-Mine/Krisuvik.pdf

Early Bio-technology and Potassium Nitrate for Gunpowder

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Early BioTechnology and the “Making” of Saltpetre

In the previous post, we discussed Gunpowder, a mixture of 75% Saltpetre (Potassium Nitrate), 15% Carbon (charcoal) and 10% sulfur.

Let’s now look at acquiring the Saltpetre.

The pre-technology (but not pre-biotechnology) source of Saltpetre is aged urea-soaked organic material (yes, this is probably considered a bit gross in these days of out-of-sigh, out-of-mind toilet habits). The aging of this material allows bacteria to convert the ammonium compounds into nitric acid. Note: this material must be protected from rain or flooding, as the desired compound is water-soluble.

To convert this nitrogen-rich organic material into Saltpetre, we can boil the source material with water. Then add a source of potassium (such as ashes from your fireplace). The resulting liquid can be evaporated to get crystals of Saltpeter (1).

We can mimic the process used by our pre-industrial ancestors by using the following steps from “The Do-It_Yourself Gunpowder Cookbook” (2):

1. Construct a filtering container by punching small holes in a 5 gallon bucket and forming a filter at the bottom by using a layer of cloth, a layer (1/2 cup) of wood ash, and another layer of cloth.
2. Fill the bucket with screened, nitrate-bearing soil/manure/guano. Leave room at the top.
3. Place the bucket over a collection container. Pour—very slowly—a gallon or so of boiling water over the soil in the bucket. You want the hot water to permeate and percolate uniformly through the soil.
4. Allow the drained solution to cool and settle. Then pour into a heat resistant container and boil the collected solution for 2 hours. Discard any salt that forms during this step.
5. After the solution has boiled down to half its original volume, let cool for ½ hour. Add an equal volume of alcohol (applejack, 12 year old scotch, or cheap vodka) and stir briefly. The small white crystals that form are Saltpetre. Collect and dry.
6. To refine further, re-dissolve and repeat the boiling step.

Unfortunately, this uses up your medicinal alcohol supply. We’ll save the production of alcohol for another post.

Another pre-industrial method is from the 5th Foxfire book (3):
1. Make a filtering container using wood slats in a “V” shape (wide at top, narrow at bottom). Line with straw-type material. At the bottom have a collection bowl.
2. Fill the V-container with nitrate-bearing soil/manure/guano. Pour boiling water over the material. Allow to permeate and percolate. Collect the leachant.
3. Repour the leachate through the nitrate material.
4. Combine the leachate with woodashes (which provides potassium hydroxide). A white precipitate (calcium hydroxide) forms and settles.
5. The woodash leachate is then boiled down until saltpetre (potassium nitrate) crystals form.

Conclusion: if you’re writing an alternative or speculative history novel, your characters will have access—through the above procedures—to the major ingredient of gunpowder. The next steps are:
1. Finding elemental sulfur or extracting it from minerals.
2. Charcoal (the way easy step)
3. The metallurgy required to smelt iron and forge gunbarrels (the ‘whew’ step).

As always, let me know if I missed something (or outright missed reality)!

(1)… http://www.rsc.org/chemistryworld/podcast/CIIEcompounds/transcripts/potassium_nitrate.asp

(2)… The Do-it-Yourself Gunpowder Cookbook

(3)… Foxfire 5

Gunpowder

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Gunpowder developed as a weapon in China about 1000 CE (common era, formerly designated AD) although it has been used for pyrotechnics as far back as 100 BCE (before the common era, formerly BC).

Weapons use probably started with fire arrows, small tubes of bamboo attached to arrows that fizzed smoke and fire. A logical next step was bombs, essentially large firecrackers.

The next development in gunpowder weaponry may have been fire lances, larger tubes of burning gunpowder that spew fire and sparks at enemy combatants.

With better quality and purity, gunpowder grew more explosive, resulting in the easy step of adding shrapnel to the fire lance. Soon, the bamboo tubes would be replaced with metal ones.

By the end of the thirteenth century, an enclosed projectile could be thrown by the exploding gasses confined in a tube. The gun was born. No longer was the smoke and fire the resulting weapon. The projectile was the payload.

This technology had reached Europe by the thirteenth century. Its use only limited by the quality of ingredients and by metallurgical constraints of the gun barrel.

Composition

Gunpowder is comprised of only three ingredients: potassium nitrate (saltpeter), charcoal and sulfur in a ratio of 75%, 15% and 10%.

Sulfur ignites at a low temperature (261 degrees) starting the explosive process. This starts the charcoal burning and breaks down the saltpeter which, consisting of Potassium and Oxygen, releases pure oxygen. This then accelerates the burning/exploding of the charcoal. The heat of this reaction produces massively expanding black gases. If constrained, this becomes an explosion.

The charcoal is easily made from wood: just burn with insufficient air. The physical structure of the wood is important for the charcoal to easily pulverized as well as to have a low ash content. Willow is a common source (and is used as a traditional artists’ medium) as well as alder, hazel wood or grape vines.

Sulfur was more difficult to find. It’s an element, so it’s either geologically available or not. Prior to refining sulfur from petroleum products or natural gas, it had to be found as a solid in the ground near hot springs and volcanic regions.

Sicily was an important source in the medieval world. Its purity was variable, but it could be easily purified. One method was to heat impure sulfur in a clay pot, the vapors given off were directed by a clay pipe to another pot where the fumes condensed into pure sulfur.

Saltpeter was even more difficult. Its chemical name is potassium nitrate, having a potassium ion attached to a nitrate ion. The nitrate ion consists of three oxygen atoms bonded to one nitrogen. Saltpeter is very soluble and is released from organic matter. One common source was privies and compost heaps from which, if protected from the weather, small amounts of saltpeter leached to the surface. The resulting white crust was saltpeter.

Manufacture

Once the ingredients were obtained, the next step was mixing them into the actual gunpowder. First the ingredients were mixed by mechanical or hand blending.

Next the mixture is ground into a microscopically fine homogeneous powder. Considerable heat can be produced, so this material was always kept moist.

In the third step, the material is pressed into cakes, producing a denser compound.

Finally, the cakes are granulated between crusher rolls. Screens are used to separate the grains. The end product is uniform mixture of black powder in the appropriate grain size. This last is important in that the size of the particles determine the rate of burning. For example, in larger cannon, larger grained gunpowder was used while rifled guns used finer grained powder.

Final Thought

Making gunpowder was a highly technical development. The chemistry wasn’t understood until the 19^th century when it was discovered that the nitrate provided oxygen for the reaction.

The critical development in the use of gunpowder was metallurgical, the development of iron of sufficient quality to contain the exploding powder long enough to allow a projectile to be accelerated out of a gun or cannon.

[end]

Not-so-primitive Primitive Skills

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In this day of hectic life and massive technology overload, many people find relief looking back to their cultural heritage, ancient coins or even archaeology. Old is interesting.

One area of growing interest is Primitive Skills, learning how one can live off the land as did our far distant ancestors. My own interest in archaeology and ancient Native American life lead me to spend several weeks in various Skills classes, schools and gatherings. One thing I discovered was that there is not very much “primitive” in Primitive Skills.

Most early societies were hunter/gatherers, heavy on the gathering. These First Peoples would need to not only know which plants were eatable or poisonous, but also their seasonal availability. One example is Camus root (1). This plant was harvested in the autumn by early northwest Native Americans, but has a toxic look-alike, unsurprisingly called Death Camas (2). Differentiating these two plants would test the knowledge of any modern day Biologist. Although I know that, side by side, the Camas leaves have a more prominent leaf ridge and the Death Camas leaf is smoother, I’m not about to dig up its bulb without a guide book with lots of pictures. Being wrong is being dead wrong.

Various plant products could also be medicinal, from pain relief to antibacterial properties. One well-known example is the bark of the Willow tree, used for the reduction of pain and fever. Aspirin was one of the first modern days pharmaceuticals made from a common plant source. Nowadays, large drug companies routinely send PhD researchers into “wild” places to try to re-discover ancient sources of medicine. My skill in pharmaceuticals is limited to using crushed Curly Dock (3) for skin rashes resulting from accidentally walking through a patch of Stinging Nettles.

Weapons would be needed for hunting animals as well as to defend reliable foraging territories. One such early weapon was the atl-atl (4), or spear thrower. This tool is a forearm long shaft grasped at one end and hooked at the other, and is used to “throw” a long flexible dart, or lightweight spear.

The extra leverage during the throw increases the velocity of the dart. The physics of the energy loading of this flexible spear has only recently been studied (5). As for my skills at hunting with the Atl-atl and dart, it’s good that my family is not depending on me to bring home a Wooly Mammoth for dinner.

Providing a projectile tip for the atl-atl dart, or even for a simple knife-edge, is a rightly refined technology in itself. Not any rock can be broken into sharp edges, and very few of those are suitable to be thinned and sharpened by knapping (6), or pressure flaking. Years of practice are required to proficiently produce projectile points, knifes or scrappers. I can usually produce a tip or knife with a few hours work, but the results are erratic and lots of good rock wasted.

Rock before (left hand holding obsidian, right hand holding a hammer stone)

Rock after (left hand holding obsidian point, right hand holding antler pressure tool)

Once one had mastered the rather refined skill of acquiring animal protein and edible plants, the next step is starting a fire. Cooked food, likely an accidental byproduct of a lightning strike, made survival easier by increasing the digestibility of complex carbohydrates and proteins (7). But lightning strikes are not reliable and certainly not safe. A separate accidental observation provided the clue to a safer method. Perhaps wanting a hole in his/her favorite walking stick or ornament, an enterprising ancestor used a rapidly rotating wood “drill”. Someone noticed that the resultant hot wood dust produced a glowing ember. This was then refined into a reliable method of fire production (8).

Work equals heat, as taught in college Physics classes. And our pre-historic ancestors put this in daily practice.

As with any subject of learning, the more I know, the more I realize how much I don’t know. The only thing “primitive” about ancient primitive skills is the level of a typical modern man’s understanding of those skills used by our ancestors in their daily life.

1. Jim Pojar and Andy MacKinnon, Plants Of The Pacific Northwest Coast: Washington, Oregon, British Columbia & Alaska, (Lone Pine Publishing, Revised Edition, 2004), page 108
2. Pojar, Plants Of The Pacific Northwest Coast: Washington, Oregon, British Columbia & Alaska, page 109
3. http://www.voyageurcountry.com/htmls/floweringplants/plants/dockcurled.html
4. http://www.hollowtop.com/atlatlbob.htm
5. http://www.atlatl.com/mechanics.html
6. John C. Whittaker, Flintknapping, Making & Understanding Stone Tools (University of Texas Press, 1994)
7. http://en.wikipedia.org/wiki/Cooking
8. http://www.natureskills.com/bow_drill_fire_making.html

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