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Science, Maths & Technology

Jonathan's Carriacou diary: Bugs and barometers

Updated Monday 28th January 2008

Jonathan Hare's Bugs and Barometers diary, from the BBC/OU series Rough Science 2

Day 1

The w(h)eather or not challenge

Felt disappointed and even slightly confused about the challenge from the start. Even if we can make the equipment in 1-2 days what good are only 1-2 days of observations? This needed some talking about and I don't think it ever happened properly - it's probably the only challenge where I felt things were not feasible from the start. So what did they actually want?

Mike B and I started to design and make up some of the various bits and pieces that a weather station might use. Barometer, hydrometer, wind speed device, rain gauge, thermometer etc.

I started on the barometer. Made up a U tube with water and used it to show Kate that the air pressure is due to the weight of air above our heads pressing down. So we go to the top of the lime factory and set the barometer and then go down to the sea and notice that the water level in the device has changed.

Now the density of air is about 1000 times less than water. So we need 1000 times less water height to balance the same mass of air. So by going 10m up (or down) in height the water barometer should change by 10m / 1000 = 0.01m = about 1cm, which it did - lovely piece of science. Can use this to measure the rough height of mountains etc.

Start on the wind speed / direction device. I spend too long trying to get the first design to work. The design works like this:

There is a flap that is attached to a wind vane. The vane makes sure the flap is always pointing into the wind. As the wind blows, it pushes the flap which by a string and lever mechanism moves a pointer fixed on the support pole. The problem which I wasted so much time on was how to get the pointer mechanism to move around with the rest of the gear and still work OK.

After several hours I drop this design for the more usual spinning half ball design. This worked very well (although the wind was sporadic and not good for testing it!) but how to get a scale or metre set up on it?



Day 2

Spend too long today trying to get the wind speed dial to work on the anemometer. Lost hours making up all sort of cogs and wheels, slip rings and spring driven tension dials etc. Just could not make it work with bits I had at hand. I think the mixture of tiredness and excessive heat over the last two programmes is making us all slower.

Finally get the barometer, windspeed (and Angie's egg timer to count rotations), hydrometer, thermometer installed in the 'weather station' and start to make our first measurements. Do a spoof weather forecast with Mike B.

Watched Mike L and Ellen being filmed doing their bug experiment. It was a quiet shot so I could not go very near to hear what was happening - looked very interesting.

Kathy makes a wonderful microscope from a bead of glass. It was amazing what could be seen. She put in a mosquito and managed to get in focus the leg of the creature. I looked in and could only see a massive black hairy piece of wood - "No," says Kathy "that is the mosquito!". It must have had good magnification.

Kathy's Microscope



Day 3

Mike B and I do a few 'sound-overs' to explain the weather bits and pieces: chaos, predictions, modern computer set-ups etc. Mike makes a much better rain gauge device and we start to record these results.

David Shulman takes me and the crew up to Gun Point to film the wind speed device being calibrated or at least shown to be working (the wind at the lime factory is sporadic, the place being sheltered). Really windy here - the thing works great. This was one of the nicest moments of the shoot for me so far. It was a bit of calm 'windiness' during the hectic recording, I think because I got away from the factory for a moment.

On the way to Gun Point we had to travel along some narrow muddy tracks to the other side of the island, some of which are quite high up the hillside. On one of these tracks we came across a boy in a car almost toppling down the steep slope. Derek asked how old he was and he said he was 12 years old. It turned out that he had taken his dad's car out for a drive, had decided to turn round on the narrow track and had run off the road. We had arrived on the scene to this sweat-covered boy who had obviously been trying for a while to sort the problem out on his own. Luckily the four of us managed to right the car and his day was saved!

The day ends with Mike L going through the results of his Bug experiment. Really nice ending. Everyone seems to be mellowing out. Had a great evening at the Green Roof restaurant just down the coast from the hotel.

Rest day

David, Mike L, Kathy, Angie and I go out to see Gun Point and also the mangrove swamp on the North of the island. I am very, very tired today. I even fall asleep in the mangrove swamp - which might be a world first for a human!

Get a dose of the blues this afternoon. Really don't want to go to the bar tonight, even the beer didn't help or even taste any good!


The tight spherical surface of a glass bead drop
Clear light directed and refracted to a spot
Insect leg, onion cell or salt crystal small
Using this device reveals them all
A skillful hand and curious mind
Amazement and wonder all the time.


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