Finding Latitude.

Currently I am reading “The Time Traveller’s Guide to Medieval England”, which is very interesting. An astrolabe is listed among the possessions of at least one wealthy merchant. This got me thinking about similar devices.

Decades ago I watched a program on someone who had spend several weeks, possibly months, in a life-raft on the open sea. Using three pencils and elastic bands he improvised a sextant and used it to measure the angle of the Pole star. Since the angle of the Pole star is equal to the latitude of the observer, he was able to sail his raft into the sea lanes, where his chance of encountering another vessel and rescue were greatest.

Here is a nice image of how such a device works. Other materials such as sticks and string could be used. This device is easily improved with a plumb-line. In the southern hemisphere you can measure the angle of the Coal Sack nebula.

Similar devices date back many centuries. If you have some cord, a kamal would be easy to improvise. Note that one example below is made from a piece of cardboard. A knot on the cord is held between the teeth and the cord pulled taunt. The bottom edge of the sight is aligned with the horizon, and the top compared with the Pole star. Different knots on the cord represented different latitudes. For example, if you wanted to sail from Alexandra to Crete you would sail north, checking your kamal using the knot corresponding to 35 degrees. Perhaps you tied that knot when you sighted Polaris another time you were on Crete. When the Pole star aligns with the top of your sight you will know it is time to start sailing west.

The cross-staff worked the same way as the kamal, as the illustrations show. It was better suited to higher latitudes. There were problems with using such a device to measure the angle of the sun, so the backstaff developed, a step towards the prisms and mirrors of the modern sextant. 

A quadrant is relatively easy to make. A number of websites show the version in the first photo. The problem with this variant is that you have to remember to subtract 90 from your reading.

It is NOT a sextant!

Easier is to use half of a typical semi-circular protractor, mount the protractor with the straight edge vertical, or mark out a piece of card or paper. When improvising navigational devices a useful thing to remember is that a circle of 57mm radius has a circumference of just under 360mm. In other words, one millimetre equals one degree. It is no coincidence that my penknife handle has three notches, one 57mm from the first, the other 5mm from the first. Thus if I make a quadrant or compass rose I can mark it in 5 degree increments. By folding paper you can accurately mark 90, 45 and 22.5 degree angles. There are several ways to draw a good circle or quarter circle with improvised means.

Or just draw around something round.

Such navigation devices can be used on the land as well as at sea. They have a long tradition of being used in deserts, exploiting the clear night skies. There are also situations where you might wish to determine the angle of a slope.

I will close with two trigonometry-based tricks:

The first can be used to determine the width of a river or road. This uses the principle of similar triangles.

Face a landmark on the far bank of the river. Turn 90 degrees and pace out a set distance, such as five paces. Place a marker (B in the illustration) and then pace out another five paces (or whatever distance you used before). A-B should equal B-C to avoid any calculations. Turn 90 degrees and head away from C. counting your paces. Every few paces look back at your landmark. When the landmark aligns with B then C-D will equal the distance between A and the landmark.

The second technique is for applications such as measuring the height of a tree or cliff. Vertical distance will equal horizontal distance when the viewing angle is 45 degrees. You can use a quadrant or clinometer for this, but you need to remember to add the height of your eye to the horizontal distance. Alternately, you can use a stick or staff and move back until it appears to be the same height as the object. Add the length of the stick/staff to the horizontal distance. You may have noticed that wood axes often have a 45 degree cut across their end. A lumberjack would sight along this, moving back until he could see the top of the trunk. Height was horizontal distance, plus the length of the axe handle.

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Masks and Coronavirus.

English has a very large vocabulary, so it is intriguing that I can still find concepts for which there is not yet a specific term. The term I am looking for is one that means to be simultaneously both “amused” and “annoyed”.

What currently provokes this emotion? Every now and then, someone passes me in the street wearing a surgical mask. I saw the same nonsense with swine flu.

 

Surgical masks don’t work that way! A surgical mask does not protect you from airborne infectious agents. It does not protect the wearer, it is intended to protect the rest of the world from the wearer. If a surgeon is operating on a patient, he or she uses a mask. If they are operating on an infectious patient, they wear a space-helmet affair with powered air filtration. Don’t take my word for it, read this or this or do some research of your own. 

Now perhaps I am just being grumpy, and every person I see is selflessly trying to protect everyone else from their own infections. If so, staying at home might have been a more prudent move. But since I am cynical as well as grumpy, I very much doubt it. Unlike thirty years ago, information on such matters is readily available. It is both impressive and depressing that people can still be so ignorant and foolish.

Want to really avoid coronavirus? A good start is to keep your fingers out of your mouth or up your nose and follow all those other manners people were once taught but are now neglected. A radical idea would be to put your phone back in your pocket. That way you might have a chance of spotting someone coughing and sneezing, or more likely threats like traffic! As a friend of mine recently remarked: “Hoarding sanitizer is stupid. You can only sanitize your own hands so many times. If everyone else around you can't, that's going to do much more to spread the disease than you only sanitizing your hands x number of times.” People fixate on sanitizer and forget old fashioned soap is an excellent anti-microbial agent.

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If You Want To Get Ahead, Get A Hood.

A few nights ago I stayed up late, and by the time I went to bed it was very cold indeed. So cold, that as I lay waiting for my shivering to warm the bed, I considered fetching a woolly hat. I thought about the nightcaps worn by characters such as Scrooge and reflected that some of our ancestors ideas were wiser than we treat them. This got me thinking about ancient clothing styles again. For a big chunk of their history humans wore cloaks and tunics, and there is no obvious logical explanation of why this has declined. Indeed, I am old enough to remember nurses and policemen wearing capes as outdoor wear.

Most modern people spend much of their time indoors. Features such as central heating, air-conditioning and insulation make this a very comfortable environment. Most of us wear just a shirt or tee-shirt, our modern underwear barely qualifying as a layer. In some places a jacket and tie is required, and cooling is turned up to a higher level, wasting energy. (Remember, the cloth used to make one ugly neck tie could be used to make two Brazilian bikinis!). When we leave this protective environment we need more insulation, and this usually takes the form of a thick outer garment we can easily remove in one piece when we reach the indoors again.

For our ancestors, things were different. Uniformly heating a large structure was problematic and resource intensive. Ironically, the peasant in his little hut would be better off in this respect than the lord in his vast castle or manor. I imagine certain select chambers of a castle had fires or braziers while the corridors and other chambers might be cold enough to fog the breath.

In general there would be less discrepancy between interior and exterior temperatures. Hence the typical clothing ensemble was orientated towards being comfortable outdoors. Travellers or soldiers might have to spend several days at a time out of doors. For the Celt, Roman, Viking, Saxon or Norman the answer to this was the cloak and tunic. These were made of wool, which has the merit of retaining some warmth if soaked by the rain. Some woollen garments had the lanolin left in or added, and might have a nap that shed rain and snow. Other fabrics such as linen and hemp saw some use, particularly in drier climates, but generally the cloak and the outermost tunic would be woollen. The early Roman tunic lacked true sleeves, or was short sleeved. Many Romans went bare-legged, or wore short breeches. In latter centuries the Roman soldier wore long sleeves and trousers, much like his earlier Germanic foes. (By this time many legionaries were of Germanic ancestry).

Tunic, trousers and cloak were not the whole story. Except in hot conditions, some form of short or undertunic may have been used. These might have been of easily laundered cloth such as hemp and linen. Underpants were rare or unknown in some cultures or classes. A noble may wear braies, while the poorer medieval man tucked the long tails of his shirt between his legs. In an era where many people could not afford large quantities of clothing such a shirt might also serve as a night shirt. Roman attire included a long scarf, worn under the tunic. For the soldier this prevent armour chaffing his neck, but the scarf is recorded as being a general item of wear. In addition to its other functions, such a scarf may have served like a detachable collar, protecting the tunic and other garments from soiling. Many tunics show trimming of the neck, cuffs and hem. This is often contrasting or decorated. Easily replaced, this may have allowed the practical life of a garment to be extended, an important consideration when many individuals owned only a few garments. 

If we look at medieval peasants and other commoners a very common item of clothing is the hood. A modern hood is usually part of a larger garment, and hooded cloaks date back thousands of years. What is distinctive about these medieval hoods is they are separate garments. Initially I thought this might be some prudent frugality. If a tunic wore out you could still make use of a perfectly good hood. Also, one only need buy or make a single hood that could be used with any of your garments. Some of this may have been the case, but the following video provided further enlightenment:

The hood was as much a shoulder cape as it was a head covering. The hood was usually lined, so it provided an extra couple of layers of insulation over the part of the body heat would be rising from.

Further on the video explains how in warmer conditions the hood can be configured into a chaperon-style hat. 

Elsewhere in this blog I have described how a shoulder covering can contribute to personal camouflage. A garment based on the medieval hood could have “garnish” applied as described here. A shaped hem adds further disruption. Camouflage cloth could be used, but this will work with any suitably neutral-coloured monotone. Being a lined garment it could be turned inside out to hide the camouflage if necessary. If made with camouflage cloth at least one side will need to cotton, so perhaps it should be made with a layer of fleece sandwiched between two layers. Some of the hoods sold for re-enactors are reasonably priced, but choice in good tactical colours is limited. Do not overlook the potential of modern versions, such as a section of poncho-liner, possibly combined with the M-51 hood attachment.

Worn as a chaperon, the hood is suitably irregular to still work as camouflage. At a distance, it looks a bit like a turban, which may be useful. One is reminded of the Mitznefet used by the Israelis.

Much to my surprise, the medieval hood has considerable potential for modern use by anyone who ventures out in cold weather.

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Hatchet Men by Richard H. Dillon.

My research for my last blog have resulted in me locating and reading a copy of “Hatchet Men” by Richard H. Dillon. This is proving to be a fascinating book, with scope far greater than just the Tong wars. Dillon includes an account of the psychological and sociological factors that contributed.

On one side, we have rampant bigotry. On the other, unhealthy isolationism. Thrown into this are some all too familiar factors. Sensationalist and mendacious journalists. Self-serving and opportunistic politicians. A greatly understrength, and often corrupt, police force that the law-abiding could not trust. Cosmetic, politically-motivated, laws that only penalize the law-abiding. Courts and lawyers used as weapons by the criminals rather than the victims. The innocent with no protection and unable to protect themselves. Good people trapped between parasitic criminals and prejudiced mobs. 

There are sparks of inspiration too. Thousands of normal San Franciscans took to the streets as the “Pickaxe Handle Brigade” and prevented the anti-Chinese sand-lot mobs burning Chinatown. Or the tenacious, often dangerous, crusade of Donaldina “Lo Mo” Cameron to rescue Chinese women from slavery.

This is a story that has many lessons for both the present and the future. Many of the conditions and problems described still exist in our societies. Within the major cities of America and Europe thousands of women have been enslaved as prostitutes.

I recommend reading “Hatchet Men”. It is a book that should be required reading in schools.

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