Quakers - Jonathan Hare's diary

Production team

Day 13 - Rest Day
Get up late, Sarah phones and tells me she is watching the Commonwealth Games on TV so I turn on the box for the first time and watch it as well. Spend today just taking it easy. Read and write my e-mails and send little letters off to Mum and Dad and to Sarah. Also start drawing the Maori designs to see which is more effective.

Day 14 - Rest Day
Got up about 9 am and pottered around waiting for Sarah to phone but we must have got our wires crossed and she didn’t phone. Did some washing and I sketched out a double spiral Maori drawing based on a wonderful wood carving in the art book.

Then walked up to the head of the Glacier. On the way I sat on the moraine rocks and wrote 7 little short stories about how each of us might get the next Rough Science invitations to RS4! Later on I made it to the Glacier face but then walked back a bit and sat down by the fast flowing Glacier River, and with the sun on my face and an amazing view back down the Glacier Valley I sat happily for a few hours very happy and content.

Did a lot of good writing today. On the way back also jotted down some thoughts. Now sitting in the Glacier Café writing it all up. TV3 starts tomorrow …….

Day 15 - Seismograph
Cold start with the challenges

It’s a terrible thing when the Earth rocks and rolls,
Earthquakes spread out and chaos unfolds
All things are impermanent that much can be seen
From atoms to mountains just part of the shifting scene
A bridge swing motion is not difficult to detect
But shifting granite and bedrock even explosives neglect.

Kate gives us our challenges for the third program of the series. Kathy and I have a seismograph challenge and they tell us that on day 3 we can test it in a quarry with explosives!!

Kathy and I make up a basic ‘pendulum’ machine/instrument. This is basically a heavy weight suspended and able to move from side to side. In actual fact, if the Earth moves the idea is that the weight doesn't move and so there is a relative motion between them that can be measured. We are not sure, however, if it will be sensitive enough to pick-up an explosion in the quarry. After all it can only measure the amount by which the Earth moves, and this is a lot for an earthquake proper but won't be much for a few sticks of dynamite however loud the explosion.

To make a record of the results we take a clock apart and attach a paper disc to the minute hand. In principle then this should turn the paper 360 degrees in 1 hour. This records nicely, but there is a problem sometimes getting the paper to be level and this leads to the chart recording dropping off the paper/not being reliable.

Tomorrow we are going to put the prototype onto the Franz Josef Bridge and record the movement due to the traffic going across. Also think about an electronic circuit to boost the sensitivity.

Day 16 - Seismograph
The seismograph seems to be working well apart from the fact that the pendulum can easily fall off the base, especially if the base is slightly off from the flat. We put the device onto the bridge and it seems to log the cars quite well. Unfortunately the bridge tends to move a lot vertically but there is little horizontal movement which is really where our seismograph has greatest sensitivity!! - it shows the Rough Science principles though.

We build an electronic addition which consists of a magnet attached to the weight and a coil of wire mounted below it on the base. The wire ends from the coil go to a simple 1 transistor amp and this boosts the signal so that the output is easy to see on a meter. Even quite small motions can be detected by this modification. Because the coil and magnet records the change of movement then this device make the position sensitive seismograph (distance) into a motion (velocity) detector. Steve Evanson asked me if we can drop the electronics however as they think it would be too complex (“a mystery”) to explain on TV.

Day 17 - Seismograph
Kathy and I modify the clock and try several ways to improve the quality of the pen / writing surface. End up soldering an additional arm to the min hand so that the paper is supported fully. This works much better.

We take all the equipment to the quarry about an hour away from the sawmill and set up the seismograph on the road. The two quarry men who are looking after us drill two large holes in the ground and we fit the base of the seismograph to these holes using two metal poles rammed in. Set up the pendulum and the clock and try a test run – but with no earthquake! The clock chart recorder makes a beautiful line and we know that everything is working very well, in fact the best it has worked so far.

Ellen has made up a really nice shelter for the seismograph consisting of a wooden structure to hold a homemade roof.

Then the Helicopter with the two Mikes comes over and drops them off with us so that we can film the end of the program sequence at the quarry. As the helicopter comes in the air blast moves the seismograph pen clean off the chart recorder very spectacular!! The Two Mikes look tired but very happy they obviously had a great time up on the mountain.

All of us get together for the official blasting and testing of the seismograph. The quarry men set up a charge some distance from the instrument and we huddle far off at the end of the wire detonator. As Kate turns the key to explode the charge there is a great blast, we feel the air blast in our stomachs and the rumblings continue for sometime as the sound echoes from hill and mountain to hill and mountain. Then we run off down to the instrument to see what it has recorded.

Kathy and I are amazed, in fact everyone is amazed – there is absolutely nothing registered on the seismograph just a nice straight line!! We have made the most insensitive device that you can imagine!! So what’s going on? We do another charge and the same thing happens!

Then we question the quarry men as to how they are setting up the charge and they tell us that they laid the dynamite on the rock surface rather than into a hole into the rock. The results now seem to make sense as this situation would make a lot of noise but not expect to move the rock much. So they drill a hole near to the instrument and load a charge into it. Now finally in this test we manage to record something – a tiny blip on the chart recording! Evidently it is much harder to make the earth move than you might think!!

Actually this does make sense. An earthquake really does move the earth by cm’s even many kilometers from the source of the quake. A little stick of dynamite would not be expected to move such a large amount of rock. But then I heard stories that even blasting going on in other quarries far off set their seismographs moving, how so? Well most modern day instruments work on similar principles to ours but they have electronics to amplify the sensitivity many 1000 of times. Our machine registers mm’s of movement on the rocks, which is not very likely but amplify this so that you can measure millionth of a meter and you would detect all sorts of vibrations and natural earth movements even many kilo meters away. So our instrument did work but it was not sensitive enough to detect dynamite only earthquakes!

A spectacular but also slightly uneventful end to TV3.