Friday, November 29, 2013

The Wounds of Richard III: an Intrusive Attack

One of Richard III's wounds is a blow that penetrated his pelvic bone after he was stabbed in the right buttock. This has been interpreted as a wound inflicted after death to humiliate him.

But I believe it could well have been struck in combat. An attacker can defeat plate harness worn with a mail skirt by moving in close and stabbing upwards with a dagger from below. This is entirely consistent with the wound on Richard's pelvis. This is easiest when the victim, like Richard, faced several assailants. Then an attacker could easily move close enough to strike a low blow upwards from behind.  But it was effective enough that even a single attacker might attempt it as in this 1403 encounter at Valencia recorded by Monstrelet:

"Then Sir Jacqes de Montenay threw down his axe, and with one hand seized Sir Pere de Moncada by the lower edge of his lames. In the other he had a dagger with which he sought to wound him underneath."

The Wounds of Richard III: an Uncovering Attack

One of the wounds on Richard III's skeleton is a shallow cut to to his right mandible. I believe that this was very probably inflicted when someone cut away his helmet strap with a double-edged dagger, leaving him helmetless. Seven other wounds are still visible on his skull and most if not all were inflicted after he lost his helmet. At least two would have instantly put him out of the fight, and been fatal soon after.

The nearly contemporary romance Tirant lo Blanc also notes this vulnerability of the sallet style helmet popular at the time. In the narrative, one of the protagonist's combats is recounted to a hermit: both the hero and his opponent tried to cut the other's helmet cord. The tactic was common enough that even the hermit, who has never borne arms but has passed some time with a skilled knight, knows a remedy: the helmet cord should be made of flexible wire wound with silk cord like a ribbon.

Tuesday, November 26, 2013

Printing Fossils

Instead of laboriously chipping delicate fossil bones from their enclosing matrix of rock, paleontologists  like Brett Nachman are printing out 3D models of the bones based on CT scans of the fossils still locked in the rock. Elegant!

Monday, November 25, 2013

Asteroid Redirect Mission

NASA has put forward an interesting proposal to use a spacecraft with electric propulsion to redirect a small asteroid, or a large piece of a larger one, to high lunar orbit where astronauts could visit and examine it and bring back samples. By small, I mean something on the order of 500 tons. In comparison, the entire Apollo program brought back 382 kg or 842 lb of samples.

Here is an overview and fact sheet. Here are more details.

NASA has also proposed placing an outpost in Translunar Space, mostly based on existing hardware. Such an outpost would greatly increase the safety and efficiency of exploring such an asteroid.

It is probably the most interesting early manned mission we can do beyond Earth orbit. With an outpost, it compares favorably with the more difficult project of visiting a near Earth asteroid in its original orbit. Austere missions to the most favorable targets contemplate missions of six months or more for a five day visit to the asteroid.

It seems to me that if you are going to spend that much time soaking up radiation beyond the Van Allen belts, it's better to spend most of that time actually at the asteroid, and it's better to be seven days from earth in an emergency than 90.

One attractive consideration for this type of mission: more than half of the cost of bringing back the first asteroid is designing and building the spacecraft. Refueling it and replacing the capture mechanism to get another will cost much less.

Also, one of the benefits of the program is a considerable increase in the power and thrust capability of electric propulsion, which will be useful for many other potential missions.

We don't know nearly enough about the insides of asteroids. It appears that many are more like blobs of rubble than monolithic hunks of rock. It would be well to know them better before we are confronted with the need to divert one in a hurry.

If the first one brought back turns it to be mostly rubble, after everyone's appetite for rock and regolith samples is sated it might be very useful to run a series of controlled experiments to determine what kind of explosive and impactor force the remainder can take without breaking up into something more dangerous. For science!

Sunday, November 24, 2013

Spin-Offs Upwards

Another lesson from India's Mars mission: a richer world can afford more space exploration!

Saturday, November 23, 2013

Cautious Optimism About Our Push Beyond Earth

I started writing this blog in 2006. Since then:

Robots have gotten better.

Sensors have gotten better.

Electric propulsion for planetary missions has become more capable.

Our ability to land a payload on Mars has increased a lot. In 2003 we landed a pair of 185 kg. rovers on Mars.  The earlier Viking landers were heavier, but that included the dead weight of the landing stage on the surface. The Curiosity rover we landed in 2012 massed 899 kg. This took a lot of challenging, complicated engineering, but we made it work.

Our ability to support the ISS is more robust.  In 2006, only two spacecraft were capable of carrying significant supplies to the ISS: Progress and the Space Shuttle.  Currently, five can: Progress, Europe's' ATV, Japan's HTV, and the privately designed and built Cygnus and Dragon spacecraft from the U.S.

A privately developed launcher, SpaceX's Falcon 9, has made several successful flights, as well as one flight of an upgraded version. It doesn't have the payload capacity of the best western launchers developed under government contract, and it hasn't demonstrated equal reliability, but its pricing is attractive enough to draw a substantial launch manifest. If it can reliably launch at a tempo that satisfies demand it could lower launch costs. There's nothing like a spade-happy billionaire to push the envelope for space capabilities.

The worst development is the gap between the U.S. retiring the Shuttle and developing a replacement. NASA's hypersonic Ming vase was retired in 2011. Unfortunately, both NASA and Congress preferred to insist on launching the replacement Orion capsule on a new launcher designed to preserve as much as possible of the former Shuttle workforce, contractor spending, and NASA infrastructure and overhead.

The institutional incentives are as obvious as the results are lamentable. Instead of simply building a capsule and putting it on a version of the existing Delta IV with some spending to improve reliability, money that could have sped Orion capsule development has been wasted on other projects, first to pay for the aborted Ares I launcher and later for the Congressionally mandated SLS launcher,  justifiably mocked as the Senate Launch System. Congressional underfunding of Commercial Crew Development is shameful.

On the brighter side, the U.S. still excels at missions beyond Earth orbit, and our Delta IV Heavy is the currently world's most capable launcher. And we have a laser-equiped robot on Mars!

But other nations have developed their own areas of excellence: Russia for flow-cost reliable launchers,  Italy for habitable modules, and Canada for robotic arms. Here's to specialization and the benefits of trade!

Friday, November 22, 2013

Welcome to Another Player in the Great Game

There's a thing we humans do. It's like the Olympics, only different. Like the Olympics, it has a lot to do with national pride, but it's harder and more rewarding. Not only do you earn the laurels for being the best competitor, but you learn things previously unknown.

In the Great Game we compete to throw robots towards other planets. This is much harder than bobsledding, so not everyone can play.  Arguably the most challenging league of all is currently Beyond Lunar Orbit. (Just putting a robot in lunar orbit is an elite club).

Until recently, the Beyond Lunar Orbit club consisted of the United States, the state currently known as Russia, a European consortium, and Japan. China attempted to compete, but failed its last attempt.

Now India has a spacecraft orbiting Earth, poised for an attempt to reach Mars.

Good luck and Godspeed, India. It is a good thing to live in a richer world. The more players, the better the game!

The Obscene Horror of Subsidized Maternity Care

One of the objections to the Affordable Care Act is that it forces people who currently don't intend to have any, or at least any more,  children to pay higher premiums than they would if they could select a policy that excludes maternity coverage.

The most obtuse version is the men that complain about being charged for maternity coverage. Dude, the insurance company knows that offering you maternity coverage costs them nothing, and you will be charged accordingly.

Greg Mankiw, who is a pretty smart guy, and usually smarter than this, presents a somewhat less stupid version:
In the law, having children has been deemed a pre-existing condition, although it is not quite described as such. Everyone is now expected to buy insurance to pay for pregnancy and maternity care, even those who never intend to have children. The goal is to spread the risk of childbirth among the larger community. 
But having children is more a choice than a random act of nature. People who drive a new Porsche pay more for car insurance than those who drive an old Chevy. We consider that fair because which car you drive is a choice. Why isn't having children viewed in the same way? 
I don't know the answer to these questions. But it does seem that fairness in health insurance pricing is being viewed very differently than fairness in pricing other types of insurance. I wonder why.
I don't. Children aren't just consumer goods. Little Porsches don't grow up to be workers and inventors and  entrepreneurs.  Children who become productive adults do. They produce surplus, and most of that doesn't go to the parent.

The person who would rather buy a Chevy doesn't care if nobody buys a Porsche. The person who chooses not to have children is usually making an implicit assumption that someone else will raise the generation that empties their bedpan and keeps the electricity running when they are too old to do it themselves. And I'm fine with that choice, as long as they don't start treating raising a child to productive adulthood as a purely selfish act of personal consumption exactly like buying a more expensive car.

So even the childless by choice have some interest being generous to those that aren't.

But where will it end? Conceivably the tax code might some day give a deduction for dependent children.

Thursday, November 21, 2013

The Proportions of the Denominations in English Mint Outputs, 1351-1485

This is a useful article for people interested in this question. Like, for example, people who are doing living history who wonder what ratio of coins they should have in their purse.

A lot of the evidence conflicts, and some is clearly biased. Coin hoards were biased towards the largest denomination available to the hoarder.  There are repeated complaints that the mints underproduced smaller denominations, regardless of their indentures.  Coins reserved for pyx trials in each denomination may not have been directly proportional to the total minted. Coin dies for larger denominations may have produced fewer coins per die.

Taking all this into account, we may still make some very rough guesses for the period covered, taking the second highest value coin in each metal as a benchmark.

For every 10 gold half nobles, there were three nobles and five quarter nobles in circulation.

For every 10 half groats, there were 5 groats, 14 pence, six halfpennies and six farthings.

Gold Coins in England 1351-1465

How common were gold coins in use England in the late 14th and Early 15th century? Coin hoards give some indication. 62 hoards were dated between 1351 and 1465. 34 contained only silver coins, 8 a mixture of gold and silver, and 20 only gold, typically all nobles. The all silver hoards averaged 7s 6d in value, a little more than the value of a single gold noble. The mixed hoards averaged 10 pounds 7.5d in value and the all gold hoards 15 pounds 6s 5d.

Gold was used, then, for sums of money large enough to make gold more convenient. Martin Allen suggests by 1377 the value of gold coins circulating in England was greater than the silver coins, although of course the number of coins was much smaller.

Allen notes a common petition in Parliament in 1363, asking that, in addition to half pence and farthings, half nobles be minted "for the purchase of food and other commodities." The government responded that this was already being done.

Tuesday, November 19, 2013

What Should Replace Obamacare?

David Friedman offers a critical view of US health insurance prior to the Affordable Care Act:
A recent post on the Forbes site offers a convincing explanation of what was wrong with the current system of health insurance before Obama, hence what both it and Obamacare ought to be replaced by. Its central point is that what we call medical insurance is in part actual insurance, protection against low probability/high cost risks, in part prepayment of ordinary medical expenditures. The reason insurance policies take that form, also the reason that most of them are provided by the employer and so not portable, is that employer provided health insurance is bought with pre-tax dollars, ordinary medical care with after tax dollars.  
 One result is that individual consumers have little incentive to be careful shoppers for health care services, since for the most part they are not the ones paying for them.
This contains a number of misunderstandings. What we call health insurance is even more complicated.  In part it is what Friedman says, but also an agent that serves to negotiate favorable pricing for the consumer in advance, which is difficult to do when you are lying on the gurney,  or even when not: an organization that buys a lot of a product can often drive a better bargain than an individual. And sometimes, as an HMO, it bundles in the actual provision of health care.

If group health care was driven purely by tax considerations as described above we would expect employers to pay for almost all employee coverage.  This is in fact rare: most employers require a substantial employee contributions, for a share of the premiums, as well as deductibles, co-pays and uncovered expenses.

In part this is because many ordinary expenses are also paid with pre-tax dollars: flexible spending accounts, health savings accounts and health reimbursement accounts also offer tax savings.

But there is another reason. If you as an employer offer to pay health insurance costs in full, you let an outside organization drive your compensation policy. If you don't absorb price increases that drive up total compensation more than you think desirable, your only alternative is to cut nominal wages or fire some employees. Employers hate doing either: neither is good for morale.

There is also another reason why employer provided insurance is common that has nothing to do with tax policy. For the average consumer, group insurance is cheaper than an individual policy for the same level of coverage because the individual policy has higher marketing, screening, underwriting and administrative costs. Even without favorable tax treatment, expect this to continue.

Then we have the argument that insured individuals are reckless consumers of health care services, since they are for most part, not paying. If that's the problem, than we've had the solution for some time: the high deductible policy. Let the insured pay the first $3,000, or $6,000 or $10,000 of medical expenses before the insurer pays anything. That will surely encourage careful shopping.

This is still an option under ACA, actually. In my state, a significant number of the ACA conforming policies have deductibles over $5,000 for a single adult.

But this runs somewhat contrary to the goal of insurance. People pay an actuarial premium to avoid unpleasant surprises. Not everyone wants to accept the potential for $6,000 in unexpected expenses for a somewhat cheaper policy.

Some changes could be made to make current law more equitable and efficient. Extend the subsidy in the market for conforming individual plans so that the subsidy at 400% of the poverty line goes to higher incomes as well. Replace the tax exclusion for employer provided plans with a capped tax credit so that this and the prior change are revenue neutral, since it's absurd that the greatest subsidy for employee coverage goes to those that need it least. Change the fine for not buying insurance to a different penalty: people that maintain continuous conforming coverage individually or through a group can't be discriminated against based on their health history but people who don't go into the separate I Thought I'd Be Healthy Forever pool when they decide they want individual coverage after all.  Remove the limit on charging older individuals more because they are more expensive to insure. Allow employers to count the cost of employer provided insurance against minimum wage requirements since it is, after all, compensation. Replace the complicated higher subsidies in the exchanges for lower incomes with an increased Earned Income Tax Credit.

These changes would be more equitable, but create losers as well as winners. I expect them to be politically difficult.

Sunday, November 17, 2013

Another Modest Proposal to Improve the SCA

I have a cunning plan. Suppose there was an SCA fraternal society, the Company Incognito. All members would swear to maintain at least two personae, one high and one low. They could both have the same name, or not, but only the high could wear their regalia and use their honorifics. The low would wear a distinctive badge and neither use nor expect to be addressed with SCA honorifics. The high, on the other hand, would be expected to always appear in public with clothing and servants fitting to their rank.

Suppose that the minimum retinue for a baron is one servant. Baron Insertname spends 1/4 of his event time as the Baron, 1/4 as Yeoman Insertname repaying his servant, and the rest as untitled Goodman Insertname doing what he wants.

Readers of Jack Vance may recognize his Kirstendale here.

I suggest that if seriously implemented this would go a long way towards improving the SCA problem of "too many chiefs and not enough Indians".

Relic of a Distant War

My father's father serve in France in WWI, in the Artillery. He brought home cartridge boxes for the 2.5 inch mountain howitzer, a deeply obsolescent piece at that time. I still have one today. It was the screw-gun of Mr. Kipling's army. The barrel screwed into the breech so you could take it apart into bits suitable for packing on mules. Kipling wrote a poem about them, first published in 1890:


Smokin' my pipe on the mountings, sniffin' the mornin' cool,
I walks in my old brown gaiters along o' my old brown mule,
With seventy gunners be'ind me, an' never a beggar forgets
It's only the pick of the Army that handles the dear little pets --
'Tss! 'Tss! For you all love the screw-guns --
the screw-guns they all love you!
So when we call round with a few guns,
o' course you will know what to do -- hoo! hoo!
Jest send in your Chief an' surrender --
it's worse if you fights or you runs:
You can go where you please, you can skid up the trees,
but you don't get away from the guns!

They sends us along where the roads are,
but mostly we goes where they ain't:
We'd climb up the side of a sign-board an' trust to the stick o' the paint:
We've chivied the Naga an' Looshai, we've give the Afreedeeman fits,
For we fancies ourselves at two thousand,
we guns that are built in two bits --
'Tss! 'Tss! For you all love the screw-guns . . .

If a man doesn't work, why, we drills 'im an' teaches 'im 'ow to behave;
If a beggar can't march, why, we kills 'im an' rattles 'im into 'is grave.
You've got to stand up to our business
an' spring without snatchin' or fuss.
D'you say that you sweat with the field-guns?
By God, you must lather with us --
'Tss! 'Tss! For you all love the screw-guns . . .

The eagles is screamin' around us, the river's a-moanin' below,
We're clear o' the pine an' the oak-scrub,
we're out on the rocks an' the snow,
An' the wind is as thin as a whip-lash what carries away to the plains
The rattle an' stamp o' the lead-mules -- the jinglety-jink o' the chains--
'Tss! 'Tss! For you all love the screw-guns . . .

There's a wheel on the Horns o' the Mornin',
an' a wheel on the edge o' the Pit,
An' a drop into nothin' beneath you as straight as a beggar can spit:
With the sweat runnin' out o' your shirt-sleeves,
an' the sun off the snow in your face,
An' 'arf o' the men on the drag-ropes to hold the old gun in 'er place --
'Tss! 'Tss! For you all love the screw-guns . . .

Smokin' my pipe on the mountings, sniffin' the mornin' cool,
I climbs in my old brown gaiters along o' my old brown mule.
The monkey can say what our road was --
the wild-goat 'e knows where we passed.
Stand easy, you long-eared old darlin's!
Out drag-ropes! With shrapnel! Hold fast --
'Tss! 'Tss! For you all love the screw-guns --
the screw-guns they all love you!
So when we take tea with a few guns,
o' course you will know what to do -- hoo! hoo!
Jest send in your Chief an' surrender --
it's worse if you fights or you runs:
You may hide in the caves, they'll be only your graves,
but you can't get away from the guns!

Just the thing for carrying up a mountain and demolishing a mud brick Afghan fort one mountain over. It used black powder, first served in the field in 1879 and was muzzle loaded. It was still used in WWI, but only in peripheral campaigns where it was better than no howitzer at all. I surmise that my grandfather met someone from a British battery that used to use them, was still using the cases to pack things in, and gave them away when he went home.

The past is a different country.

The Great Divergence

It looks like Europe started to pull away from Asia in economic performance a lot earlier than previously thought, in the case of Italy as early as 1300.

Europe as a whole had a critical advantage over China: being further away from Mongolia, and also benefited from the introduction of of the vertical windmill. Italy was improving shipbuilding as it married the capacious hull of the northern cog to a handier multi-mast Mediterranean rig, and introducing some powerful and important business innovations: double-entry bookkeeping, foreign exchange and insurance contracts, and the legal fictions that allowed Christians to be bankers.

We take these technologies of doing business for granted today, but the difference between having them and not having them was huge.

Saturday, November 09, 2013

Hoops in Canopies

Details from, top to bottom: Petrus Christus Madonna and Child with St. Barbara and a Carthusian Monk (Exeter Madonna) c.1450, Bible Historiale of Jean de Vaudetar, 1372,   Judith and Holofernes from the Speculum Humanae Salvationis MS Hunter 60 (T.2.18) 1455, Annunciation Martin Schongauer Engraving ca. 1484/5, Annunciation Martin Schongauer, Painting.

Conveniently, the very sheer material of the Exeter Madonna's canopy allows us to see the hoop that spreads it.The indoor canopy of light fabric requires only a slender hoop. In the last three images I believe we are seeing a round curtain rod of slightly narrower radius than the hoop that spreads the canopy, with widely spaced brackets providing enough clearance for the curtain rings to slide along the rod to open or close the canopy curtains.

Friday, November 08, 2013

Medieval Tent Structures

From the top: Images 1-3 rope spread roofs 1: Equestrian portrait of Guidoriccio da Fogliano (detail) Simone Martini 1328-30 2-3 St. Martin renounces his arms (details) Simone Martini 1312-17. 4 Tent roofs supported by radial ribs. BL Add. 12228, f.150 (detail) Roman du Roy Meliadus de Leonnoys c. 1352 5-6 Pavilions and tents with vertical slats in the walls King René's Le Cueur d'Amours Espris c. 1457 7: Pavilion or tent with a rigid peripheral structure at the shoulder: Agnolo Gaddi: The Dream of Emperor Heraclius ca. 1385-87

Medieval tents used at least four different structural designs.

The tent spread by ropes alone is recognizable by catenary sag visible in the profile of the roof and walls, the shoulder attached to closely spaced guy ropes or crow's feet; although even so, there may be visible horizontal sag between the attachment points, and by guy ropes that descend no steeper than the roof profile, which typically produces a broad footprint for each tent on the ground.

Tents with radial ribs in the roof are clearly recognizable when the roof profile  is convex. The yurts and gers of Central Asia still use radial ribs, with a roof profile that is either straight or convex.

Tents with walls stiffened by slats or battens are suggested when the walls slope without any indication of sag or drape, when a contemporary illustration suggests that they are present within channels in the wall, or when documentary evidence mentions them. King René's accounts for 1453 mention "rods for the wall of the said pavilion" and rods are also included in the itemized materials for a pavilion probably written by a Milanese tailor around 1540 in Il Libro del Sarto.

Finally, by the second half of the 14th century it seems to have been common for medieval tents to have had a rigid internal frame at the shoulder of the tent, circular, polygonal, oval or rectangular as the shape of the tent demanded, with circular the most common design.  The Dream of Emperor Heraclius shows many of the features of this design. A limited number of guy ropes, if any, steady the tent. They descend at a steeper angle than the roof profile, and are insufficient to produce the roof plan shown by themselves. The tent valance forms a perfectly smooth cylinder.

Sunday, November 03, 2013

Hardware Beneath Pavilion Shoulders in the Morgan Bible

From the Morgan Bible, 1240s, details of folios 9r, 10v, 27v, 34r and 42r.  If there was a rigid hoop within the pavilion shoulder it would have been fairly straightforward to attach these brackets so they hung as shown here. If not, not.

Friday, November 01, 2013

Pavilions Retaining Their Shape While Falling

From top: Morgan Bible MS M.638 (fol. 3v) Detail, 1240s, (BNF, FR 2643) Jean Froissart, Chronicles fol. 180 Flanders, Bruges 15th Century, BNF Français 364, fol. 125 (Hannibal passant les Apennins, Romuleon, c. 1485-1490), BL Royal MS 18 D II f. 82v c. 1500.  and The Encampment of Henry at Marquison 18th c. copy of a 16th c. painting of Henry VIII's Boulogne campaign of 1544. Details.