Deer and Detergents.

A friend of mine mentioned the other day that deer can see into the ultra-violet range. Naturally I did some research myself to confirm this, and found this interesting article.

I learnt that deer can see in colour, but not very well at the red end of the spectrum, which is why red and orange clothing can be used for deer hunting. (Bird hunting is another matter. Birds tend to have very good colour vision in general).

 

The UV sensitivity of deer vision has some interesting implications. Many laundry detergents include whitening agents that reflect UV-light. In short, what to our primate eyes may be a nicely camouflaged jacket may look distinctive and out of place to a deer. I suspect as this information becomes more widely known some clever company will market a detergent especially for hunters. If you are going to use this as an excuse not to wash your favourite hunting coat remember deer have a very good sense of smell too!

The discussion of laundry soaps reminded me of this statement made about US Woodland pattern camouflage garments:-

“… When they are brand new this pattern choice isn’t bad. With daily (duty, military) use and washing the pattern starts a light graying process and doesn’t stop until they are lightened and useless for their intended purpose. With that said some of the woodland fatigues do start to "brown out" and that is a good thing when it happens. With normal civilian wash and wear this seems to happen more often. With most military personnel we notice the graying on a larger more pronounced scale.”

            If this observation is accurate a likely explanation is in the laundering process. Civilian owned garments are less likely to be washed by industrial laundries.

            As many of you may be aware, the US Army has had considerable problems with its ACUPAT camouflage. Supposedly this pattern is a mix of grey, sage and tan. Most garments you see in use seem to appear to be various shades of grey and dirty white with very little contrast between the elements. Is it possible, perhaps, that some of the problems are a result of the Army’s laundering system? Worth investigating.

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Umbrella Fighting : All the Links.

           I have just acquired a new umbrella for my girlfriend and joked that she could read my "How to poke people with a brolly" blog. With that in mind today's blog will gather the links about self-defence with an umbrella together in one place.

Part One Fencing Parries with an umbrella.

Part One and a bit An Interlude.

Part Two Swagger stick techniques.

Part Three Commanding the blade or brolly.

Part Four Offensive techniques.

Vigny on Umbrellas.
Light-hearted article from 1897
 

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Direction Finding by the Moon.

The other night I was looking at the crescent moon. Many readers of this blog are doubtless familiar with how to find direction from the moon, but some will not be, so indulge me for a moment. By drawing an imaginary line between the horns of the crescent and extending it down to the horizon the approximate position of south can be estimated if in the northern hemisphere, or north if you are in the southern hemisphere.

 

Idly I wondered if the angle of this line had any relationship to the latitude of the observer. I recalled there was something about navigating by moon in the Japanese Manual of Night Movements.

“Although it is difficult to determine direction by the position of the moon, the latter has the advantage of being recognizable even on nights when all the stars cannot be seen. The moon crosses the meridian about noon on the first lunar day, and it moves about fifty minutes behind the sun every day. Therefore, if the age of the moon be known, the approximate passing of the meridian can be easily computed. Its approximate age can be computed from the shape of its bright portion.”

Not really that helpful! Something may have been lost in the translation. Most websites I looked at had no answer but eventually I found this interesting paper and found the answer is “no”.

I later confirmed my latitude was 51 degrees so an angle of either 51 or 39 would have been expected if the hypothesis had been correct. The range of angles the terminator can be at as it approaches and passes meridian will vary with latitude, however, but this has very little application to practical emergency navigation.

 

An alternate method for direction finding by the moon involves remembering that the sun sets in the west and rises in the east. If the moon is up in the early part of the night, or in the evening before the sun has gone down the illuminated side will be the western. If the moon is observed in the latter part of the night or in the morning then the eastern side will be illuminated. In this context “latter” and “early part” of the night are defined in relation to the median point of the night, also known as Solar Midnight. In other words, the middle of the period of darkness rather than the chronological “midnight”, 12:00am or 0000hrs on the clock. This is more of a secondary method since if you can see the light and dark parts of the moon you can use the terminator method to find north or south. I suppose you could make a crude estimate of the time by establishing where south or north is located and then observing which side of the moon was illuminated.

You can also estimate direction from the moon using the shadow tip method. This is often illustrated using the sun but the principle is exactly the same using the moon. Place an object such as a stick in the ground so that it casts a shadow. Mark the tip of the shadow. Wait for at least fifteen minutes so the shadow has time to move. Mark the tip of the shadow’s new position. A line drawn between these two points will run east-west. The first point you marked will always be west, the second east. Easy for me to remember since my name is “West” so “West comes first!”. Both the moon and the sun move from east to west and in the northern hemisphere they are always in the southern half of the sky so shadows cast have varying degrees of northward orientation. A line perpendicular to the east-west line will be north-south and the shadow will be in the direction of the pole of the hemisphere that you are in.

The advantage of the shadow tip method is that you can use it when there is a full moon and you could not use the terminator method. In the daytime you can use the shadow tip method when the exact position of the sun cannot be seen because of clouds, so long as there is enough light to throw a shadow.

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Christmas Creep - it begins again, already!

                A recent topic of some discussion on the internet was the Christmas tree in Paris that is widely regarded as looking like a butt plug. Most of us, however, missed the real issue, which is why is a Christmas tree of any form is being erected in early October?

 

 

                I was in a restaurant with my girlfriend this Sunday. They had a Christmas tree of beer cans in the window. It was the twelfth of October! Last year I wrote on the topic of Christmas Creep and predicted that it may start even earlier this year. Already a TV station boasts that they will be broadcasting 24 hour Christmas movies. I so hate being right!

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