Monday 7 July 2008

Making time run backwards

In this modern day and age nobody has enough time in their day, yet the mere fact you're reading this suggests you have some time to waste. Fear not! After reading this guide you'll have the power to make time run backwards... sort of. The aim of this post is to get a normal clock and make it tick in the wrong direction. This has all sorts of uses from an accessory for your model(?) time machine to really annoying and confusing people in an office or anyone who owns a clock really.

This is a very quick and easy thing to do and doesn't need any special tools or skills. I can't guarantee you won't break the clock you're using, but it's a risk you'll have to take.

You will need:
  • A cheap clock (mine came from Ikea for about £1
  • Something to prod with. Keys work well
  • A suitably evil sense of humour
  • A new clock background (optional)
Method:

1. Examine
Take a good look at your clock and try and work out which way the second hand is going. If all is well it should be ticking at a steady rate of 1 tick per second. If it's going slower then you're probably looking at the minute hand. If it's going faster I have no idea what's wrong. Also have a little look at the back of the clock. You'll see a nice shiny black box. It's similar to the black box they have on aeroplanes in colour, but not in many other ways. This is the movement. You'll never guess what is does. You may notice the rather attractive design on the clock in the picture. I elected for perpetual Pimm's O'clock or Hammer Time when I was designing. You'll also notice the rather helpful red arrow I added to show you which way it normally goes.

2. Start removing stuff
The first thing you want to remove is the battery. I'll let you work that one out for yourself. The bit to get rid of next is the invisible plastic bit on the front that stops you prodding the hands during normal operation. On my clock this held in place by three little plastic tab things which you get at from the back. Prodding these with keys seems to be a fairly effective way of getting the front bit loose. Once you've got that off remove the hands as well. They should come off with gently pulling. Keep the battery, invisible plastic and hands in a safe place. You'd be amazed at how tricky it is to get a photo of something that isn't meant to be seen.

3. Carry on removing stuff
The next bit to remove is the movement. Remember the little black box we discussed earlier? It's normally held in by a couple of little clips which can easily be overcome by some keys. Prod at it until you're holding the beautiful black box in your hands. There's the little wheel to set the time and the battery compartment on one side and little white sticky out bits on the other that the hands were attached to.


4. Open the box
If your name is Pandora and the clock is yours then you should probably stop now just to be on the safe side. Otherwise carry on. The next thing you have to do is open the box. To do this look for two little clips on the sides. Keeping the box pointy-white-things down pull at one of these until the back comes off to reveal the inner workings of the clock. You should see four little white cogs, a copper wire coil and a sideways U shaped plate going through the coil. There's a photo below of what it should look like. If you're looks much different to this then give up now. My expertise doesn't extend that far.

5. Remove the cogs
The little white cogs have to be removed but before you start pulling away at them take a minute to note where they go, which order they go in and how they mesh together. Be careful about the order you take them out. Refer to the picture for the order I removed mine in. You need to make sure you can put them back in the same order that they started in otherwise the clock won't work. While you're examining the picture take a quick peek at the copper coil and the U shaped plate. That's what we're going to be playing with next.

6. Gently...
At this stage you should have the movement open and looking fairly empty with a little pile of cogs next to it. You should have left a copper coil with a U-shaped plate going through the middle of it. This step is the one which will, with any luck, make the clock run backwards. What you need to do is carefully and gently slide the plate out of the coil. It should come out easily enough with some gentle persuasion. Once you're holding the little piece of metal (on my clock is was actually two piled up) you need to flip it over length ways so you can see the other side of the plate. Now slip it back into the coil so it sits back where it was, just with the opposite side of the plate facing up. Looking at the photo on the right of the plate back inside the movement the curvy corner of the plate (bottom right) started off at the top right and the square corner started at the bottom right.

7. Put it all back together again
Once the plate has been flipped put all the cogs back in in the right order and put the back on the movement. At this point you can put the second hand back on and the battery in to see if a) you're clock still works and b) whether it's going backwards or not. If all is well the take the battery out and the second hand off and put all the pieces of the clock back together. Just before putting the hands back on would be a good time to add a new background to the clock if you so desire. Once it's all back together put the battery back in, set the time (remembering that it'll be the mirror of a normal clock), put it back where you got it from and watch the confusion spread.

I had a clock like this in my room at university halls in my first year. People would come in and it would usually take them quite a while to notice something was amiss. After a day you'll be able to tell the time as well as you can on a normal clock and after about a year a normal clock will, occasionally, catch you off guard and confuse the buggery out of you.

Questions and comments are welcome.
Enjoy!

p.s. Sorry this isn't a video guide. I realise that it would have been far clearer but I lack a suitable camera and the will to faff about with youtube. Hopefully it's all suitably clear anyway.

Sunday 1 June 2008

How to cross a weir


We all know the situation: you're on a walk in the country side and you've got a bit lost. Your map tells you you'll be able to get back to civilisation by simply crossing the river and walking along a road for 100 meters. Sounds easy until you find out from a friendly old lady driving past that there aren't any river crossings for miles. She also mentions there is a weir going across the river in her back garden that you're welcome to cross.

You're now faced with a dilemma. Do you walk for miles and walk across a bridge in perfect safety or trust the old lady that it's possible to cross the weir (which, just to make things better, is rather high and fast at the moment) which would mean at best wet feet or at worst drowning, but making the walk home far shorter.

I, along with anyone else in the same situation, chose the weir. This is a brief guide on how to cross a weir in reasonable safety. Remember crossing weirs isn't recommended!

Before I begin with the guide lets talk a little about weirs. Weirs are designed to control the water level in a river, and act as a small dam. According to wikipedia there are various types which I won't go into but this guide shall be talking about broad-crested weirs. These have a level bit at the top which you can stand on. Most weirs are longer than the width of the river (wikipedia will explain why) so remember you'll be walking quite a long way.

Anyway, enough faffing about, lets get on with the guide. Just follow these few simple steps and you'll be across in no time:

1. Talk to old people first
Old people know all about local surroundings as they generally have nothing better to do with their time. This means they'll know if it's safe to cross the weir in question, what the current conditions are like and be able to give you useful tips. When I was in a weir crossing situation the old people were very friendly and very helpful although their useful tip of "make sure you can swim" was less than encouraging.

2. Try and find out if you're trespassing
It can be hard to tell who owns a weir so try and make sure you're not trespassing on anyone's land. You're progress will be severely hampered if you are shot half way across

3. Check where the weir ends
Because weirs don't go straight across the river they may not end where you think they will. They also don't go in straight lines all the time. They often go in semicircles (ish) which means you'll be walking a long way and not making much progress. The main thing to watch out for is whether or not you'll be able to get onto the bank onto the other side. It's all well and good getting safely across just to turn back because you've reached a sheer brick wall

4. Check there's a good place to walk
When crossing the weir you walk across the top where the water is lowest. You need to make sure there is a suitable flat platform on the top to stand on. Try and keep your feet between the two red lines on the (high quality) diagram.

5. Look out for the edge!
The main purpose of weirs is to act as a mini dam. This means that there will probably be a drop at the edge of the weir (again, look at the diagram) into deeper water. Assuming you want to stay dry you need to keep looking where you're treading to make you don't tread onto deep water. This water will be calm so you probably won't drown if you fall in but nobody likes being wet.

6. Keep your shoes on
As much as you want to keep your feet dry it's definitely best to keep your shoes on because the weir will be slippery. The platform spends it's life underwater so there is a very high chance there will be weeds and other goop that will be trying to slip you up. Shoes will help. If you're wearing flip-flops then the weir will try its best to take these off your feet which can be interesting

7. Face the current
By standing so you're facing into the current you'll create less resistance against your feet so it'll be easier to move along. You probably won't be standing perpendicular to the weir. The angle the water flows over it depends on the design of the dam and you'll probably have to change the angle you're wading at as you move across. Be careful to keep checking the direction you're walking. You don't want to be walking off the edge of the weir. You'll probably be able to feel with your toes where the edge of the weir is and stay back from this

8. Slow and steady wins the race
Moving slowly and steadily is far less likely to throw you off balance than if you rush. It also means you get longer to appreciate the free wash your legs are getting

9. Take a big stick
This point should probably be further up the list but seeing as you're probably not reading this half way across a weir I can't be bothered to put it further up and faff with the numbering. If you take a big stick then you can test the depth of the water you're crossing. It's means you'll avoid suddenly stepping into empty water and help keep you dry. It also means you have a way of fighting off angry farmers on the other side after ignoring step 2.

10. Use your common sense
If there are obstructions you need to get round, get round them logically. If you need to move down a step on the weir try and hold onto something or someone and be careful. If the water's too deep or too fast then go back. You can always give up and walk to the bridge.

11. Fall forwards
If you are about to fall over and you can stop it try and fall forwards into the calm water behind the weir rather than into the turmoil below it. There are likely to be very strong currents at the bottom and even the strongest swimmers may get pulled under. The obvious solution is not to fall over.

12. Go straight to a restaurant afterwards
All your friends will appreciate you turning up to the meal you'd arranged to go to late and smelling of sweat and river. I know mine did! Wet trousers and feet and muddy hands are always welcomed by even the best restaurants. You'll even have a new dinner table anecdote about your newly found weir crossing skills.

Hopefully that will tell you everything you need to know about crossing a broad-crested weir. Remember to be careful and only wade across as a last resort (or second to last if it's a really long walk to the nearest bridge)

The author takes no responsibility for any injury caused by using this guide. It's meant for entertainment only and should be used with extreme caution, if at all. The reader is responsible for their own actions. Don't try and pin your cock ups on me!

Wednesday 2 April 2008

Creating chaos on the computer

The fact is, that I'm a sucker for pretty pictures and there is a wealth of natural prettiness in the crazy world of strange attractors (I use the word natural in the mathy sense, obviously)

One of my favorite toys when it comes to computing is an absolutely gorgeous application called ChaoScope, a tool for visualising and creating high quality images of these incredible systems.

Here is a small rendering I created of the Julia set in quaternion space:
It's possible to spend hours at a time getting lost in the world that this application lets you into. Download it and play for a while and, if you need your programs to have a "purpose" then, I can promise you that you'll never be at a loss for a desktop background again.

Friday 25 January 2008

An introduction to the blog that PWNS.

Hello and welcome all to People Who Know Stuff (PWNS).

The idea of this blog is for the people who know stuff to post things they make, do, consider, muse and hypothesise. Will it be useful? Probably not. Will it be interesting? Maybe. Will it contain science? Almost certainly. It will be updated as and when we do something new we consider worthy of telling the world.

The People Who Know Stuff:
So all of our beautiful readers know who you're gaining knowledge from we have each written you an introduction about ourselves. If we find more People Who Know Stuff then they may be added later.

Anthony

Name: Anthony
Nicknames: Winston, Ant, twerpy
Life currently involves: Studying maths at the University of Bath
Pet hate: Slamming doors. People not washing up my (kitchen) knives
Favourite book: Hitchhikers' Guide to the Galaxy, Douglas Adams
Favourite number: 5
Height: 191cm
Hair: Dreads
Planned posts: Various anti door slamming devices, coffee shop catapult, recipes, growing things
Favourite quote: Can we have sex now? No, we're talking about graphs.

Paul

Name: Paul
Nicknames: The Bear
Life currently involves: Studying maths at the University of Kent
Pet hate: The human condition, having to walk.
Favourite book: Surely You're Joking Mr. Feynmann/ What Do You Care What Other People Think - R.P Feynmann.
Favourite number: aleph-0.5, which may or may not exist.
Height: Short
Hair: Curled Mess
Planned posts: Cutting out shapes, recipes, things that computers can do, fun facts.
Favourite quote: It's okay if you find this difficult, even the students at Warwick found this difficult.