About New Forest trig pillars and other interesting facts
A fascinating history of cartography from the inimitable perspective of Mark and Hugh
Cartography. Mapmaking before the advent of radio waves.
In your youth you must have made a map or three. There might have been friends who were coming for dinner and needed to find their way to your secluded house. Or a neighbour who wanted to know where to find a hardware shop. Maybe it was when you were at school and you and your chum drew a map showing your hideout. A picture is worth a thousand words and all that. Here we have the essence of a map, a pictorial explanation of topographical features. These days we have the most incredible maps of all, everybody uses them and they are called collectively, Google Earth. These astonishing satellite images reveal the most intricate detail. We can even tell if the neighbour has finally cut the back lawn! There’s no hiding your laziness behind a six-foot-high fence when a satellite image will reveal all. You are being watched!
But it wasn’t always like this, cartography used to be a grindingly tedious matter. Pioneering too.
A pace, a span, a yard, a chain, whatever!
Accurate measurement is a relatively recent phenomenon. It was the French who developed the metric system. Those who have worked in engineering will know that all measurements are given in millimetres. Not in the US though as they are very conservative and strictly Imperial (but don’t knock it, their system was good enough to put men on the moon). Not that long ago, measurements were a little more arcane. If you wanted to measure the height of your nag you would simply have used your hands. Apparently, brave souls actually place their hands upon these unpredictable and powerful beasts in order to measure the height of the thing. You wouldn’t catch me doing it. It was reckoned that the average width of a hand was four inches. The measurement is taken from the ground to the top of the animal’s withers. At times ponies and horses have to be measured before entering certain races. Nowadays a metal rod with a horizontal bar at the top, a little like an upside-down L is used. The result might be, say, forty-eight inches which equals twelve hands. Similarly, we used to talk of a yard which was a pace; of a span, the distance between the outstretched little finger and thumb. Or perhaps a foot, well you can imagine what that might be. All in all, measurement used to be an unregulated and unreliable business.
Imagine that before the advent of standard accepted units you had to make a small map, the kind that we described earlier. Perhaps one that would take a walking pal from Beaulieu to Bailey’s Hard by way of the riverbank path? Perhaps, the type of sketch that might take your friend to the nearest local hostelry? Naturally, the sketch would never get him home as it would be dark and he might not walk in the straightest of lines. However, you will endeavour to get him to his refreshment. The first concern is distance. What tools are at your disposal? It can only be your legs surely? Off you go counting the paces before you come to the first corner. With the number of paces recorded neatly in your pocket notebook you then consider the angle of the corner, whether it is sharp or smooth. Then, off you go again, counting and recording.
So far, we have just managed a simple line sketch. For a moment, consider the complexity of an Ordnance Survey map. There are symbols galore depicting objects such as churches, with a spire or a steeple. Tracks, whether they be for those travelling by foot, bicycle or pony. Houses, villages, points of interest, places where the view is worth a pause. Finally, the most important symbol of all, PH. Public House, aaaah. The level of detail in these maps has to be studied to be believed. I had a friend who used to work at the Ordnance Survey, he told me that a colleague managed to (falsely) draw some contour lines in the shape of a Mickey Mouse head and ears. I’ve always meant to check. Apparently, it’s on a map of the Isle of Wight.
Ain’t no mountain high enough baby.
A simple plan view of the area is fine for most but for those who need a little more accuracy, we need something called a contour line. Try to imagine a cake that I have just cooked (I cannot cook). Instead of the usual flat-topped affair, your writer has constructed a catastrophe of a cake. A cake so awful that the sight of it could reduce Mary Berry to inconsolable tears. A cake so like the Himalayas that no chef could ever hope to decorate it with icing. Imagine that I was to take a knife and cut, neatly and horizontally, through my little sponge mountain range. Once complete we would have a cut line that, wherever you measured it, would be the same height from the kitchen table. This is how map makers tell us how the land lies. The contour line on a map will have the height of the line noted upon it somewhere. Once more I pick up the knife and I make another cut below the first one. You can imagine that on a steep bit of sponge there will be a small distance between the two cut lines. However, on a gentler slope the distance across the sponge will be greater. It’s no different on land, where we have a gentle slope it takes quite some distance to attain an increase in height of fifty feet. If we were on a very steep slope the distance across the ground would be much less. When you study the contour lines on a map you can actually see the hills, the gullies, the peaks. It’s all there.
I am constantly aware of my position.
I once knew two expert map readers and the ability they possessed was astonishing. One was a keen orienteering runner and I was teamed up with him once. I remember we came to a clearing and as we gathered our breath, he announced that the map was wrong. We were to go through the thicket that wasn’t marked correctly. He was right and we won the race. Another could actually navigate on featureless rolling hills. All he had was contour lines. These people are rare, for us mere mortals a careful and considered study of the OS map will usually get us there. Usually.
I am temporarily unsure of my position.
This is Army code for ‘I’m completely lost!’ Well, it happens. The military tend to take map reading quite seriously. After all, you really need to know exactly where you are when you call in an airstrike or a bombardment. To not bomb yourselves is considered good tactics. We civilians measure angles using degrees of which there are 360 in a circle. The military use an angular unit referred to as ‘mils’ of which there are 6400 in a circle, a considerable step up in accuracy. Also, the military use something called a romer, this is a small pictogram normally imprinted onto a transparent compass base. This helps the user to break down each map square into further divisions, thus increasing accuracy.
This is all old hat you silly duffer.
This is what you might be thinking or muttering as you read this and indeed, you are right. I am a silly old duffer and these methods are indeed old hat. The old methods are fast being forgotten. As we have mentioned before though, a map and a compass are truly cordless and also as an added bonus, no signal is required. You would be bananas to plan a trip up a mountain without these indispensable items. Mountain rescue teams have had to rescue many that have relied exclusively on electronic signals and battery power; both have proved vulnerable.
Our trig pillars.
You may have seen the odd trig pillars as you drive across the forest. There’s one close to the edge of the road that runs between Hilltop and Dibden Purlieu. These were erected by the Ordnance Survey and are designed to support a device called a theodolite. The pillars are like icebergs in that there’s more below the surface than there is above it. Many of these trig pillars are gone now, buried beneath new housing developments and such. Ours are largely untouched and, whilst they remain standing, they are a reminder of just how difficult and time-consuming map making used to be. In the early part of this article we described how early map makers used body parts as crude rulers. For more reliable maps, and in order to measure distance with greater accuracy surveyors used glass rods butted against one another. A theodolite was constructed in order to measure angles. This is a device which measures angles both horizontal and vertical and is essential to the map maker. The first took an unbelievable three years to construct and measured three feet across. However, it was found to be such a wonderful instrument that another was commissioned soon afterwards.
Two of my favourite writers, Arthur Ransome and A. Wainwright were avid sketchers. Their books are peppered with tiny maps and chartlets. The next time your grandchildren have a pen and paper perhaps see if they can draw a map of the street. Gently tease them ‘Granny wants to go to the post office but she’s forgotten the way’. It should be interesting to see how they respond.
See you later, navigator.
More tales and cartoons for Lymington and the New Forest from Mark and Hugh
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Meanwhile, if you'd like to read previous articles on diverse subjects written by Mark and illustrated by Hugh's cartoons here they are, click the links embedded in the titles:
Pony drifts and pannage in the New Forest
A journey from the New Forest via Lymington
The brilliance - and persistence - of Marconi
Equality in the skies
Bees pollinators par excellence
Cordless home entertainment
The joy of sheds
When the Isle of Wight was just Wight
Pond Life in our Forests
Rufus Stone and Sir Walter Tyrrell
Graffiti through the ages
Freedom of the roads
Watch the birdie
Unstoppable momentum of nature
Socially distanced socialising
Calshot Spit, a curse for mariners...