down and up

In a narrow street in Cambridge there is a hole in the tarmac in the shape of an elongated heart. Around the corner, when the light fades from the sky the sundial high up on the church wall tells the time of the orange lampposts' night. Sometimes I look down and sometimes up.

Recently I have been using my old inline rollerblades to get from A to a range of other letters, and so now the pavement has a new meaning. Now I feel the down. The pavement has more texture than it did when I was just shoe soles and bicycle wheels.

It is incredibly smooth and I weave between the walking people without ever needing air to come between my wheels and the ground, only elements of the figure eight. And then it is slightly less glass-like, it is the sandstone paving stones, and the sound comes out in a strange wavering tone that sounds like ghosts are underneath. But then there are older paving stones with the deep cracks between, and if the weight is too far forwards you will trip, so you must sink back a little. You will never flow here, and the precision of where the next pushing step must fall absorbs everything. At the special paving stones made of little bobbles that tell the pedestrians where they should line up to cross the road, if you hold your wheels in a very straight line for a while you can slip exactly between the bumps that otherwise would judder and jar through your legs and right up your back. Cobbled streets are obviously out of bounds. Then there is the road. Sometimes the road is so rough that the wheels cannot move with any pace and need constant, vigorous encouragement, even though your tremor-ridden legs ache for the glassy surface to come back.

Sometimes I look at my feet and sometimes at the sky. Now I feel with my feet. I want to feel the sky.

Run

Mother moved house. She moved when I wasn't there, but I've seen it now. We had Christmas there last year and that was the point at which it became a family house. We all helped to keep the fire lit, and the complex procedure of Christmas dinner was kept in check by a thorough list detailing the time-before-take-off of each person's part.
Mother's house has hills and woods now. I tried running through them last time I was there. At first there was a stream making enough noise to keep the footfall on leaves into a delicate but slightly frantic pattern. But then there were only woods and fields and all the focus settled on the ups and downs of the hill path so that the head felt it was ploughing through the softly muddy ground. I let the feet tumble down and down till we reached the road. The carving had already been done there. But then there were the lorries passing from behind with their invisible drivers, passing at such regular intermittence that in the quiet spells you could feel in your skin the next one growing in the distance behind until it was big enough to take its place in the air it would push past you.
The next day I ran in the other direction. I ran alongside a canal, and although it didn't have the rush of the stream, its quiet, steady companionship was more than enough. Sometimes the land at the side rose up or fell away, and sometimes a bridge wanted everyone to cross to the other side, but the path and the water stayed at the same level the whole time so that the feet and the eyes could go their separate ways. At times they were miles apart. At a certain point there was a tunnel. It wasn't that anything about the path changed. It was just that the land closed overhead so that the water on the ground glistened black and the thin splashes they made shot back from the roof to accentuate the tentativity of the feet. Once I was through the tunnel there didn't seem to be any point in continuing further so, a little more confidently this time, I plunged back into the darkness and ran home.

Calculators for kids!

At home now with my love of calculators, it is time to share them with the children. Yes, the children.
The Whipple Museum has a wonderful wealth of calculating tools from the past few centuries of the western world. There are slide rules (including groovy circular and cylindrical one which boost up the multiplication power), abacuses, tiny little Napier's bones, big clunky mechanical calculators from the early- to mid-twentieth century, little stylus slide adders and Curta calculators (exceptionally cool) from the 1950s. And of course, a bordering-on-incredible number of hand held electronic calculators from the 1970s and early 80s, some remarkable for being the first of some kind or other (scientific, programmable, touch sensitive, etc), some remarkable for being sensually either thrilling or distasteful to a high degree, some for visual flair, some utterly unremarkable apart from their adding to the general impression of the sheer quantity of these things that so flooded the markets, and some that from a great distance look like flies.
Via the medium of the video-conference, I am going to talk about these tools of calculation to classes of 12-14 year olds, from four different schools all at once. Magic. Then they are going to get together in little groups and do their own research project on them, including designing a mathematical game based on their tool, and in a second video-conference they can present the fruits of their labour to me and the other classes so that we can all discuss. Hopefully it will be fun and give them happy enthusiasm beans.

Silence of

Silence of the children-thought
as blown on carriage train to nought,
with buckets from the mind-well slowly
brought to stretch the light of dusk where
shadows pierce a heart of sorts
and salt marks out the eyes.
Smite not now the over-pass,
where thundered air can breathe at last,
where distance flies us close enough for
bruised lips to return to laugh
and delight is compromise.

Parameters of touch: calculators are go.

On seeing a clunky, quirky, sleek or sexy calculator from the 1970s in a museum or in a museum catalogue, surely you would be disappointed not to be able to reach out and touch its eminantly clickable keys. I know I would.
And yet here I am, in a museum workspace, with 436 such calculators at my fingertips, making our database ready to publish a catalogue of the collection. I could help you. I could give you vicarious calculator sensuality.
So, I am not merely recording dates and what type of battery these things took; I have devised a language system.
To try and make it clear, I made a few semi-artificial parameters of the act of pressing these little keys .
First is the length of travel: how far the keys can be depressed. This works out simply as short-, medium-, or long-travel. Texas Instruments are generally very short travel, for example.
Next is the process of depressing the keys. Just like the keys of a piano, those of a calculator can be differently weighted. Degrees of resistance. Thus the keys vary between being very light and very heavy to the touch. Some of them require serious finger power. Some are so light you hardly knew you pressed them, and then some, like the Sinclairs, seem so heavy that perhaps the calculators are only meant ot be viewed. Of course, Sinclair can get away with that: theirs are the only calculators that actually pass as sexy, especially the Sovereign.
During depression, the keys may also be 'squashy'. Casio keys are a typical example of this. Note that lightness to the touch is necessary but not sufficient for squashiness.
Then we come to the behaviour of the keys at the end-point of depression. It became fashionable to make calculators whose keys clicked upon depression in the 1970s (in the marketing blurb this was a 'positive click'... helping you have a positive calculator experience, of course). But there are all manner of types of click: it could be soft, muffled, loud or prominent; it could be dull, bright, flimsy, hollow, metallic, or could even give a faint rattle. Some manufacturers ignored clickiness entirely; their keys, in my language, have 'a soft manner of depression'. Decimo tend to be like this. The phrasing here is a little awkward I know, but it is better than my earlier solution, where the keys simply had 'soft depression'. Poor things.
Finally comes the behaviour of keys on their return. They can be increadibly springy and bouncy on some makes. Surprisingly, springiness seems to be almost entirely unrelated to squashiness. A key that squashes limply on depression can suddenly spring straight back out at you on release: a remarkable feat if ever I saw/felt one.
Shape comes into this as well, but only insofar as some are concavely shaped to the finger.
Throughout all of this I have tried to refrain from normative language. Some calculators have such utterly crap keys that quite frankly I'd prefer to take the calculator to bits and gawk at its groovy interior than actually use the damn thing. (Actually its getting to the point where I want to do this to most of the calculators, invalidating my attempt at abuse, but you get it, I'm trying to be emphatic here: some of their keys suck). And then some calculators, some calculators have dream keys. They really do. I want to use language like 'perfectly' weighted, and ridiculous things like a 'delightful click.' But I try not to talk in those kinds of terms. I'm trying to be objective about this. Ha!

I would very much like to buy a little something.
One of those little somethings that a little peckish someone decides they can excuse to themselves in one way or another.
It will surely be some kind of pastry or chocloately thing of some sort. It is that time of day. It is going to be a treat. And I am going to revel in tastification station, lap upall the sensual glories of luxurious deliciousness that such a thing could offer. I must choose carefully.
I must take each one into my mind's eye, hold it up to the light, turn it over slowly, sink into it for a moment, and see where it would leave me were I to choose it in reality. Each one. If the decision is going to be a good one, I can't take anything for granted.
But there is a pressure squeezing from outside, a pair of eyes trained on me, trained yet devoid of expression, a pair eyebrows cocked expectantly yet hardly out of place, the frosty force of that inaudible, inner, impatient sigh. Like a clip around the ear, she wants to know if I have chosen yet. She is worried about the other people, because I came in before them and it would violate the rules of accurate and appropriate queue formation if she were to serve them before me. But I don't care about her queue; I have a much more important queue of imagined pastry samples to deal with before I can possibly even contemplate her human queue.
I am going to have to take a deep breath and hold in mind that this decision is far more enjoyable than she remembers.
And then I think I will find a bench and have a little contemplative sit-down in which to appreciate the end-product of such a momentous decision and subsequent purchase.
How super.

The turning-in-snow diaries

It turns out, the activity of skiing is centred most primarily around turning.
Going straight down the fall-line of a slope is a most distasteful practice, involving little in the way of skill and much in the way of uncontrollable speed. There is nothing wrong with speed. But it should always be controlled.
The way to do this is to turn.
The way to that, however, is tricky.

When you are slowing yourself down, your skiis are roughly perpendicular to the slope, parallel to one another; they are pointing across the slope. You want to make them point the other way. But how could you possibly acheive this, when the middle stage in the process surely necessarily involves pointing them straight down, picking up too much speed and no longer being able to shift them one way or the other at all?

The answer lies in your weight.
Your weight is on the downhill ski (the one of the two that is further down the slope) so that you can push right into the ground to slow down. What you are aiming to do, therefore, is gently to transfer your weight from one ski to another.
When you do this, what it feels like is that you become, for a magical moment, entirely weightless.
It is a piece of mental trickery. You lift your mind away from the ground and let your skiis slip neatly underneath you, until you make (mental) contact with the ground again. At this point you push them right out to the other side and dig them right into the ground again. Your body feels as though it has stayed in the middle. You're leaning totally inwards, facing right down the slope. It just your bent knees, locked together, that are pushing your feet and the skiis attached to them out to the side.
So then you can zoom, bouncing like this from side to side, down, down, down.

But this is only the case in a certain type of snow.
There are many types of snow.

Just now, here, the snow is prone to being rather icey. The above method of turning becomes untenable. You need to dig the edge of your ski in if you are going to control yourself. The very edge. The uphill edge of the downhill ski, to be precise. The uphill ski doesn't matter too much; just forget about it for now.
What we are doing now is called carving. They can be very wide, long turns when you're carving. In fact, right on the edge of that ski, knees bent, weight slightly further forward than in softer snow, you actually pick up speed. You feel it when you get it right. Normally turning slows you down, but when you get it just right, they suddenly start accelerating underneath you in a wonderful glide. You can use this if there's a gentle slope that normally slows people down; you can glide past them. But you can also use it in these icey conditions we're talking about, to carve out a graceful curve that lets you come down the piste in total control.
Of course, when you do the crucial point of the turn, you are still doing the weightless trick, but it's not nearly so pronounced as in the short, sharp turns above; it is much more gradual.

Seascape

Mostly sent down to the waves.
Seemed to stay there longer each day,
covered in sand, buried in play.
Seaweed for hair
if we wanted that.
A fine mesh of hand-crafted water channels we built, avoiding the fray,
shells over ears,
eyes pointed away.
A fine game of jumping just when it was about to break,
of plunging underneath for as long as we could take,
of seeing what we could dredge from the bottom only to shake in each others' faces.
And in a way, we were quite happy playing like that,
as if it were only us and the sea.

Further croissant-related missions

The other day, I went to Nottingham to chat with the guy who is the expert on what I was planning to do my Ph.D. on, and I was trying to be open-minded with regards the possibility of doing said Ph.D. in that very place. So, in the hour before our meeting, I took myself to his department's little cafe, purchased a coffee and a swirly danish pastry thing, and sat down with the only of his articles that I hadn't yet read. Now, I had intended to try out their croissant, as a pseudo-jocular-but-in-fact-very-serious method for evaluating the place's potential lurability. But there was no croissant. This left me in the awkward position of having to base a highly important evaluation procedure around a foodstuff in which I really do have no expertise. I was not particularly enamoured with the danish pastry - it was incredibly sweet, with outrageous amounts of icing and stickiness, and, unsurprisingly since it was not a croissant and was not aiming for this quality, had almost no fluffiness at all and could even have said to have been rather hard. I felt slightly unsettled.
There was, however, a sign in the cafe declaring the price of croissant.
So, I could make a judgement based upon the experience with the danish pastry, which is bound to produce a disproportionatley low score since such a thing is intrinsically inferiour to croissant.
Or I could make a withholding of judgement to some as-yet-undefined point in the future - on the grounds that the availability of croissant is usually dependable and I just happened to be there on a bad day - which future point may not even take place until the decision of the place of the Ph.D has been made, in which case the croissant really has been bypassed altogether leaving the decision entierely at the mercy of more conventional means.
I find this a most awkward and dissatisfying situation.


On a lighter note (oops, unintentional but harmless pun!), I have recently been surprised with a lovely croissant in B-Bar. On previous occasions, the B-Bar croissant has been quite dry and even a little tough, and has really presented no other option than to be submerged in coffee prior to consumption. Now, not one too make too hasty a judgement, and as one who works around the corner from B-Bar, I gave the place another chance. And the croissant was pretty much perfect. So B-Bar is unreliable but with great potential. I had not previously thought of factoring time into the croissant criteria.

The Croissant Diaries

Surely the most satisfying start to the day involves croissant. This is how it is for me at least. But some croissants are more conducive to a state of morning tranquility than others, and sometimes it seems important to keep a precise mental log of where success in this quest has been found.

Of course, above and beyond the intrinsic properties of the thing, context also matters.
For instance, my most formative and thus highly prized croissant experiences involve a cluster of siblings curled, sprawled and draped around my mother's bed on a Sunday morning, as Bach's cello suites or perhaps Vivaldi's Nula in Mundo Pax Sincera floats up the stairs, and the gentle light of the expansive East Yorkshire skies dances on the wide river Humber before curving in through the window. Here, the croissant in fact functions, on one level, simply as a medium for the imbibement of coffee, through the operation known as 'dipping'; or rather, the croissant is so intimately bound up with the drinking of coffee that to consider either one alone would be an injustice to the other. On another level, the croissant is merely a semi-arbitrarily chosen obligatory passage point for the occurance of a vitally important ritual gathering and bonding within the family. So the croissant's status is in fact both historically contingent and a partial sideline to another consumable. But nevermind all this. What I have said is, the croissant has a special place of importance for me because of two interrelated factors (family plus coffee), whereas what I meant to say in this section was, that the setting in which the croissant is consumed plays an important role in the level of enjoyment the same may bring.

But I wanted to talk about real croissant.

Now, you'd think that the Bread Man in the market would sell lovely fresh croissant. Indeed, that is what I thought too, but in fact they are a little dry and slightly doughy. In order to make up for this, in which the bread stand very nearly succeeds, the croissants come with all manner of distractions: apricot or apple and sultana filling, chocolate and almond and a swirly shape, chocolate and a twisty shape... but these frills seem to accentuate the lack of the rare treasure of the plain croissant.

Reluctance to go to one of the Nadia's (the reluctance being due to a long-held suspicion against this slightly-too prosperous local bakery - how are there quite so many of them?) was recently overcomeby the writer on the grounds of its ridiculously convenient proximity to last year's house, and in fact the results were surprisingly good. They microwave it for you if you like. A difficult decision; overall the warmth wins out, but the microwaving process does somewhat deflate the thing into a flat state of greasiness.

Of the supermarkets, it would appear that Marks and Spencer remain ahead, although the new Sainsbury's organic croissants are extremely close competitors. The freshly baked Sainsbury's croissant is pretty good also. The other packaged Sainsbury's efforts have much to be desired, and even the Waitrose croissant, though excitingly large, doesn't have the all-important degree of lightness.

I think we can safely say there are two important factors to croissant success: lightness and butteriness. And fluffiness. Fluffiness so as to prevent the flaking into coffee upon dippage. Three factors, then: lightness, butteriness and fluffiness. Although, having said that, it is highly likely that fluffiness is the product of both lightness and butteriness, and thus is the all important factor. So, one factor: fluffiness. (No one expects the Spanish Inquisition!)

Very recently, I tried the Presto croissant. This is really very impressive indeed. I can find little to fault in this croissant.

Funny side

Small boy, aged 3, 4, 5, who knows, standing on the square stone steps that bottom an obelisk war memorial as Saturday-morning people busy past, small boy saying earnestly
Daddy, look, daddy, this is the funny side.
Boy almost hugging the stone wall of the sides of the step, moves around the corner to his left, boy has just realised that
Daddy, this is, daddy this side is also the funny side; both of these sides are funny sides.

I don't know what the other sides were, because slowing down as much as had enabled this sight so far was already taking me dangerously away from the Saturday-morning-person categories and there was no need to cause a scene.

But what a discovery. Now every time I go down that street I know that those two sides there are the funny sides.

Astro

Today has suddenly switched into an astrology day. Sudden switches seem perfectly justifiable given the weather. So this is my birth chart.


It used to freak me out with that one line sticking straight through the middle. But secretly I quite like it. It says to me, focussed but with spurts of completely alternative input that maybe work to keep things balanced, but not too balanced that they're dispersed.
Actually when I did my own chart there were one or two more aspects (an aspect is an angle between two planets that is denoted particular importance, like 60 or 90 degrees say, and which is represented on the graphical chart with a line), but I think that was probably because I wanted a more exciting-looking picture. And it was exciting! On mine, there are two other lines coming from the moon (the only planet on the right-hand side of this chart), which join up to both ends of the purple line thus making a lovely isoceles triangle that the red line then bisects. The whole thing appears as a sail, and so looked rather nice. It also ended up being part of a larger configuration of aspects which basically works as a pointer to the planet on its own, in this case the moon, making that planet, its sign, its house etc particularly important in the interpretation of the chart as a whol. Alas, however, the computer program that churned this drawing one out thinks that the planets just weren't quite exactly where I had had them. I suppose it's no big loss. I am rather attached to that configuration actually. I must learn to move on. Such a pretty sail.

The Stone Bomb

Patrick Wright - cultural historian - is seriously cool, and here is a recent article on the first Anti-Air War Memorial that confirms it. Really, do read it!

Admiralty Compass Observatory

Below: 1917 picture of a workshop.
And now... some extracts from a 1932 article in a national newspaper about the (tremendous) ACO.
Note the tensionous jostling of rustic and high-tech imagery in the mens' room, and the (when seen detachedly) hilarious separation of gender, both literally (different rooms) and by association (painting, faces, gardens etc).
So, the journalist is being taken on a tour of the buildings....

“Then the workshops – the faint murmur of machinery and the rustling tick-tick-tick of lathe-belts passing round their pulleys. Men manipulating queer metal shapes from the complicated internals of gyros, men peering through magnifying glasses, men gently waving magnets near hesitating compass cards, each man with the blank, abstracted face of concentration.”

Next...
“Three girls in a room apart, touching the small cylindrical faces of aero compass cards with fine paint brushes tipped with radium paint.”

And then, in the Magnetic Test Room...
“high French windows looking out upon the garden. Two women were bending over compasses on turn-tables, one a boat’s compass, one an aero compass. Had they been busied with embroidery the scene would scarcely have been more peaceful.”


Ha!

1925 was a good year.

Isn't this beautiful?

Photo-history of the aerocompass

This is the first decent aerocompass.

On hearing of pilots' compass-troubles Captain Creagh-Osborne, of the Compass Department, put a submarine compass in a bedding of horsehair to counter the effects of the aeroplane's vibration and took it up in Colonal Cody's plane. This was only a year after Cody's first powered flight and made Creagh-Osborne the first Naval Officer to fly. Yippee.

This little beauty is from 1915, when Creagh-Osborne was working in close communication with a few manufacturing firms. Their joint design has fancy new ways of dealing with vibration (rubber, springs, blah), a vertical and simplified reading card to make things easier for those pressured pilots, and an inverted pivot to make the card spin in a more groovy way.

Of course, the RAE (precursor to RAF) over at Farnborough wanted to have a go too, and came up with this rather inelegant effort, also in 1915. It has a much slower period (i.e. the needle oscillates much more slowly) than those of the Admiralty Compass Observatory; this was the RAE's solution to the wild behaviour of the needle when the aeroplane turns. Known as 'northerly turning error' this problem was due to the fact that when the aeroplane banks, the needle begins responding to the vertical component of the earth's magnetic field. We're not interested in that component. It really sucks. It means that when you turn towards the north the compass under-indicates the turn, so that you turn too far and may even enter a spin, and when you turn towards the south it over-indicates it so that you don't turn enough. The idea of the slow period compass is that it registers turns so slowly that these problems don't have time to take effect, and the pilot doesn't end up constantly over-correcting his course.

The ACO, however, began employing two Proper Scientists in about 1918. With a military-industrial-academic complex under full swing, what should appear but an aperiodic compass! This was really very cool. The needle didn't oscillate in a silly way when the plane had finished a turn, and yet responded quickly. By now the compasses also has a better way of dealing with the problems caused by flying at high altitudes. There the low pressure and temperature would cause the liquid to contract, and so result in the formation of bubbles, which screw up the movement of the needle system. At first they used expansion chambers; then Creagh-Osborne asked his manufacturing buddies to put in an airtrap, which was a little better. Really what they wanted to do was make the liquid out of pure alcohol, but then this would cause the paint inside to dissolve, so that a) the markings couldn't be read so well and b) little bits would get into the liquid. It really was tricky business.

From 1922, separate compasses for the plane's observer/navigator and its pilot were designed by the ACO. Above is a rather lovely observer's compass, complete with azimuth for taking bearings and serving as a bombsight, and the picture before was a pilot's compass. This 'observer' entity existed for a short, 50 year period and then dissappeared again, poor chap.

Then they had the Second World War, and all sorts of other stuff happened.

bombs <-> aeroplanes <-> people/mail

1919, Jan 16th:

"It is perfectly certain that we are on the eve of a tremendous development in commercial aviation... It is true that the machine designed for war is not the best type for commercial purposes, but it is equally true that the one designed to carry a large number of passengers or a heavy weight of mail or goods is quite capable of carrying a corresponding weight of bombs"

- Editor's comment, Flight magazine, the first journal of the aircraft community (hooray!)

Life drawing class

First to look around in furtive discovery: 80 degrees to the left, model the central pivot, a limply suspended woman emerges draped on the paper of someone who could not bring themselves to include the chair on which the model sat; 60 degrees to the right someone else draws four or five of the others in the class as they draw, cluster of people surrounding and nearly drowning out the model, and it's like the fascinated gaze at distant bird hides facing you from the darkness inside your own, looking out and in at the same time, stopping the slip into imagined invisibility. Determined denial of the situation's artificiality on my left and frenzied over-preoccupation with it on the right: ever-so-slightly closer to the latter.

Second to look at the model herself from my place, from behind and to the side of her, paper still blank, soft curve of cheek and glimpse of pleasantly perked-up nose but all blankly fading into unexpressive mouth and petering-away chin, charcoal in hand has no response, a whole body, tumbling down from the face, overwhelmingly present, sinking into chair, landing in solid flat confidence where the lower of her crossed legs settles on the floor and she had been told to leave on her shoes.

Absent minded drift of charcoal here and there around that body before settling into a close-up focus on the strong back of that lower leg and the flat of that sandal shoe.

Then a long gaze in and out of focus right at the model gradually to realise that what is being seen could only be described by cascade. The eye pours and falls in downward-curved jumps and leaps: tumbles from a hold on top of the shoulder down the loose arm, tracks back up to beautiful ray of shadow following path of arm down back, stop-gap switches to her hand on the arm of her chair where arcs of fingers point gently to the floor even while gripping tightly, and crash-culminates in up-and-down splash over three floorbound slashes where narrow leg of chair stands between shapely, crossed legs of model, and so much momentum by now that it - the gaze - springs right up to the hook on the shoulder again. And all the while the face doesn't seem to enter into it.

So now I have fixed upon this idea, this waterfall of body and chair, but the next drawing still gets caught up with areas where too much working-in pull the eye to a static, over-informed rest. I am told this by she who wanders around quietly and engages with us intensely, and instructed sternly to let go of representation, to draw the raw idea not all of this stopping and starting. There follow a couple of hesitant attempts, forehead frowning, each time absorption and frustration both growing, but then flying charcoal flowing leaves me with a piece that seems too strident and aggressive to me, but seems actually to startle this teacher of ours.

A pulse of muted exitement: she seemed held up on a string for a moment, briefly lost in the drawing, as if feeling the faint connection with a sliver of magic that means something has been captured. Well, after that response, it seemed time to leave the A2 paper and embark upon a last half hour basking in the freedom of A1. The light outside had become dimmer, but even so, the way each subtle shift of shade was standing out so strongly on that body was partly that by now I had slightly become it. Drawing some-thing/one you have entered into like that can no longer be frustrating: there is only a contented dream-state. And so ended my first experience of life drawing.

Southwold's Cathedral

Character directionally variable, through a slow circling process.

And it looks better in watercolour...

Navigation by the stars

Just as twentieth century compasses had almost completely taken my world by storm, I found that sextants, more specifically bubble sextants, were being used for celestial navigation of aircraft right until the middle of the Cold War! Yes, that's correct: navigation in aeroplanes by heavenly bodies. Here is Commander Weems demonstrating, and here also is an early 1920s example of such a device. A skilled pilot was required to keep the plane steady whilst measurements were being taken, and on early commercial flights, the pilot would turn on a special light to convey to customers his wish for them to cease their centre-of-gravity-upsetting meandering and be still for a while. This system was mainly used over sea; pre-Second World War air navigation over land involved pilots trying to follow roads and railways, looking out for the occasional inscription of a placename on a roof, and occasionally taking a brief stop at a farm to ask the way. Of course, it all got a lot more high-tech during the war when black-outs made things somewhat tricky, and an innovative fervour produced rather more swish-looking sextants, a modification of sun-compasses termed an astrocompass, gyro-stabilised distant reading repeater magnetic compasses, compasses with bomb-sights attached...