have a half-crown?’ into his ear. When there was no response, she crept around to the other side and whispered, ‘Can I have a crown?’ into that ear. There was silence for a time, then without opening his eyes, he murmured, ‘Go back to the half-crown ear.’
In 1971, the government of Prime Minister Edward Heath formally abolished the old coin values and went to a decimal system (based on the number ten). He hoped to modernise Britain, breaking those ties to the ancient past. New coins were issued, with the five-pence piece referred to as a shilling to help with the transition. A pound was redesignated as 100 pennies, so that the 5p piece was still one-twentieth. New green one-pound notes were issued, replaced in 1983 by the first pound coins. Later, two-pound coins were issued for normal use. Some special-edition five-pound coins are produced each year and gold sovereigns are still minted. The bank notes at the time of writing are for five, ten, twenty and fifty pounds.
It is worth noting that these are artificial systems. Whether a pound (or a dollar) has a hundred pennies or 60, 240 or even 360 is a matter of choice. We chose to keep 60 minutes in an hour, 360 degrees in a circle and 24 hours in a day. Yet some numbers are just more useful than others. 240 has 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 16, 20, 24, 30, 40, 48, 60, 80, 120 and 240 itself as factors – 20 in all. In comparison, 100 has 1, 2, 4, 5, 10, 20, 25, 50 and 100 itself – just nine factors. In that way, 240 is more useful than 100, both in trade and in teaching maths.
The history and stability of a country can be read in its currency – and knowing the road behind can be useful in judging the road ahead. Of course, it is possible that before the 21st century comes to an end, all transactions will have become digital and coins will have gone the way of the dinosaurs. That would be a shame – there is something comforting about a handful of change clinking in a pocket – along with two thousand years of history.
Rubber-band aeroplanes are as old as, well, rubber bands. You could use the skills in this chapter to make a simple one, with a propeller. That’s part of the reason why we’ve put this in the book: it’s astounding what you can do with balsa wood, superglue and ordinary thread. The other reason is that an ‘ornithopter’ flaps its wings. They’ve been around since the 19th century as toys, but they’re still impressive. You can buy a kit or a complete plastic one easily enough, but it is immensely satisfying to make. At the time of writing, the world record for indoor rubber-band-powered flight is 21 minutes, 44 seconds, held by Roy White of America. Our ornithopter will fly for just a few seconds, but it’s still worth it.
YOU WILL NEED
Needle-nose pliers
Superglue
Thread
Elastic bands
A razor blade or art knife
Tissue paper or a supermarket plastic bag
Wire. Paperclips will do, but we used 1/16in brass rod, because it felt a little stronger
Electrical wire (for the plastic covering)
Oil or grease
⅛in aluminium tubing
A few coffee-shop wooden stirrers (or ice-lolly sticks)
A hard plastic bead
Spars of balsa wood
Note: ‘Super’ or ‘crazy’ glue refers to the group of fast-setting cyanoacrylate glues. Although it is apparently a myth that they were developed to close battlefield wounds, they are sometimes used in that way today, to seal cuts where it would be difficult to stitch. In other words, superglue sticks well to balsa wood, but it sticks amazingly well to skin. In the course of making this ornithopter, we stuck our fingers together many times – and our fingers to other things, including the tube of glue itself. Acetone is your friend when it comes to removing superglue, but please try to avoid pulling your fingerprints off. They do grow back, however. There is clearly potential for injury here, so find a dad and make him help, but don’t let him do all the tricky bits. Remember: scars are fine. Having to go through life attached to a superglue tube is not.
In balsa wood, you’ll need a couple of spar pieces to act as the body and a couple of thin spars to form the backbone of the wings. Hobby shops sell balsa in all shapes and sizes. It’s not expensive stuff, so you should be able to get a selection for a few pounds. The point of having more than you need is (a) for when you tread on a wing spar and snap it, and (b) because, as you’ll see, balsa is really useful. It won’t be wasted.
We formed the main body with four pieces. The thin spars are ⅛in thick, ½in wide and 7in long (4mm × 13mm × 17.5cm). The thick ones are ½in × ½in square and 2in long (13mm × 13mm × 50mm). We added blocks of ½ × ½in batten beneath as well, to hold the rubber band later.
Up to this point, it’s all symmetrical. Choose an end to be the front and cut three pieces of aluminium tube. You could use brass or plastic. It should be the right size to allow your wire to pass through.
With a razor blade or a hacksaw, we cut all three tubes the same length – ⅝in (16mm). As a general principle, it’s worth sanding the rough edges. Two tubes go on the top, parallel to one another, while the third goes at the bottom. It’s vital they don’t come loose, so we cut a groove for the bottom one, glued them all in place, then wound cotton thread around the entire assembly. Cyanoacrylate glues essentially form a hard plastic as they set, with a little heat given off. The result is impressive and incredibly strong. Honestly, the application of superglue on balsa was very satisfying. Once or twice when fiddling, a crack was heard. A dab of glue on the hairline crack, good as new.
The crank is the only tricky part of making this, so here it is. The rubber band will be held by one end and wound at the front. (We did try a rear-winder on the first attempt, with a cork attached. That actually worked pretty well, but we’ll keep this simple.)
The problem is how to turn that rubber band rotation into an up-and-down motion for the wings. A spinning disc doesn’t work – it’s impossible to get the wings to act together. What works is a staggered crank, which lifts two rods at slightly different times.
The wire comes out of the bottom tube, leaving enough room for a plastic bead (fake pearls work well). With the needle-nose pliers, make a 90-degree bend to the left, looking at it from the front. It should be as sharp as you can make it – you do not want that bead to work its way around the corner. After ¼in (6mm), make another 90-degree bend, heading away from the main body. Leaving enough space for a small wooden batten – say ¼in – turn back in a 90-degree bend, parallel with the first bend.
So far so good, but that upside-down ‘U’ has to be twisted to create an angle of 60 or 70 degrees.
Looking down the crank, it will look like this:
