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Rough Science 3 New Zealand: Mike Leahy's diaries: Shakers

Updated Tuesday 27th February 2007

If finding gold was easy, we'd all be doing it. Mike Leahy recounts his prospecting experiences.

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The first programme had been extremely hard work for me. I think that the others (especially Kate) thought that I was a right whinger, but I was suffering with a cold, regular asthma attacks and with my broken tooth could neither eat or speak properly.

As usual, I wake up for the first day of filming well before dawn but can soon tell that it is cold and dry outside. This means that we will probably have a dry sunny day.

It doesn’t all go smoothly at the beginning of the day because Steve (the boss) took me aside to tell me that while we were being filmed ‘being natural’ during the evenings I had messed up some takes by swearing a lot. I hadn’t even realised that I had been doing it. Bummer! Time to try harder.

Today is to become a vintage Rough Science day. Together with Jonathan and Kathy I am to try to construct an automated gold panning system in the hope that we can get hold of alluvial gold more efficiently than in the first programme.

Our target is 0.55g, which should be easy enough, but making the equipment will be very labour intensive involving lots of banging, sawing and construction work. Thank goodness we have three of us on the case.

Like the others I know very little about gold or gold panning, so common sense and some idea of what gold panning devices we have seen in the past is all we have to work on, and of course science.

The design of our automated panner is based on a device, which was used in the nineteenth century and is called a cradle because it rocks

We have a sketchy idea of what it looks like, and use it because it’s quite easy to automate although I think it’s fair to say that we all have our doubts about how much of an improvement it will be over a simple sluice. In addition to rocking the cradle we really need to move water.

Water is the single most important component in obtaining alluvial gold. Without water the gold sticks to rocks and pebbles and there would be no way of separating them. In fact some gold mines are pretty much made up of a cliff face and a hosepipe. For now making a water wheel and constructing the cradle is enough work, so we leave the pump until day 2.

By late afternoon we are getting somewhere. The cradle looks beautiful and just needs riffles and some sacking put in to catch the gold.

J’s water wheel is up and running and all that is left to do is work out a good way to connect it to the cradle and the (yet to be constructed) water pump. The weather is brilliant.

As I gaze over to the moon climbing above snow-covered mountains on the horizon I’m happy.

Typically the Gold is in the ‘wrong place’

It was another fine day, meaning we were to be very cold at first. As I wander around the sawmill trying to get my limbs to move properly and my brain in gear the view is amazing. There is a thick frost everywhere and the cobwebs are decorated with ice making them look like delicate lace.

Time is a real problem with this challenge. We haven’t only got the cradle to finish but we have to connect it to the water wheel and construct a water pump. I start work on the water pump and at first try using half a tennis ball as a valve.

The ‘pump’ consists simply of a drainpipe which will be immersed in the water. A broomstick with half a tennis ball can then be slipped inside it and when moved up and down should pump water.

The half-ball, because of its shape, acts like a one-way valve, very similar to the valves in your heart. When I push down, it should collapse and less water pass it to fill the drainpipe above, but when I pull back up, the half-ball should return to its original shape and bring the water up the pipe to the top.

The first tests are promising, but when I try a longer pipe the valve isn’t efficient enough. It’s time for a re-think. A new valve is made up of a disc of wood which fits snugly in the drainpipe. There are holes drilled in it to allow water through when I push the broomstick down, but when I pull the stick back up a flap of rubber closes over the holes as water tries to flow through them. This seals the wooden disc, allowing me to draw water up the drainpipe. It works very well

Linking the cradle to the water wheel is easy and involves the use of another broomstick. The water pump is powered in a very similar way to the cradle. We go through a dry run for the camera and are then set to go to the river. This is not easy because our ‘inventions’ were huge.

When we reach the river we are immediately downheartened. It appears that the task of making an automated gold panner is impossible if only because of one fact. Fine gold is carried by water and is believed to be moved during floods.

Like any particle suspended in water, it is most likely to ‘fall out’ when the water slows. This tends to happen on the inside of river bends and behind boulders. In the first programme we chose to work on the inside of a bend and managed to get over half a gram in very little time.

This is all very well, but the water wheel needs a strong current. These tend to be found on the outside of river bends. As the Whataroa River is quite wide at the location where we are working, our task looked hopeless.

There is no way that we can find water fast enough to turn the waterwheel anywhere near the gold. Bummer! We wander around the side of the river near the gold for ages trying to find a decent current and finally plumped for a place sixty or seventy metres away from the area that we planned to dig.

The tail is now wagging the dog - sort of. Our automated gold panning device is going to be more labour intensive to use than the simple sluice.

Nice grub.

I'm beginning to feel more comfortable with the evening filming now. I don't swear and I am trying not to wind Pippa up (the assistant producer who is filming us).

Five Months to Christmas

I leave my hut to be greeted by another beautiful frosty morning. A Kia is squawking from the top of a tree silhouetted by the glowing mountaintops, illuminated by the still invisible sun. Kias are supposed to be rare, but we see and hear plenty of them. As usual day three is a terrible rush.

Looking down from the high bank it is soon evident that we have another problem to overcome. The river has changed height in the night, meaning we have to go through the whole tedious task of finding a half decent current again, so the first hour of the morning was pretty much a repeat of the previous afternoon. Bummer!

When we do find a reasonable location for the waterwheel it is even further from the damn gold. We also have to stick the cradle high up on a large rounded boulder, which is hardly ideal.

This leads to two problems: firstly the cradle is balanced very precariously and is difficult to rock, but secondly the pump that I have designed to lift water three feet or so above the river surface is unable to propel it up to the cradle. The pump is great at lifting, but once the water poured out of the top it is not under pressure, so can’t be forced up a hose.

Because the pump is more or less useless here we decide to bin it. This is a crying shame because the two tasks that really need automating - water pumping and digging - are going to have to be done manually.

All that is automated now is the rocking motion of the cradle, not something we would have needed at all with the old design of sluice. This is hardly our fault though, because we had no idea where we were going to put the machine when we were building it. In a way it is inappropriate technology, much like some of the huge hydro-electric schemes in developing countries.

Although the automated system isn’t all we hoped that it would be, we really do think that it would be better at trapping gold, if only because it is better made and includes some new features – sacking and ribbed rubber mat.

At first even the rocking motion is a bit disappointing. Some adjustments to the bolt, which attaches the driveshaft (broomstick) to the waterwheel, and placing some boards under the rockers of the cradle helps but we are still critically underpowered.

Our only other option is to try to speed up the water current. By using plywood boards and boulders we manage to channel the water current a little, and by timing how long each rotation of the waterwheel takes we scientifically work out the best angles to place all our paraphernalia.

By mid-morning we still haven’t started panning. This is terrible because ‘day’ three always finishes at about 2 pm to allow the filming necessary to finish the programme.

Our main concern is that we won’t get more gold than on programme one. When we eventually do get everything going the full nature of our failure to make a workable system soon becomes evident because the work needed to keep our new baby monster fed with sand and water is pretty intensive.

The gold bearing mud is a long way away so we opt to use large twenty five litre buckets. Digging the stuff out and carrying it along to the machine where J and Kathy are pouring the water and sand onto the cradle is seriously hard work and after an hour or so I am ready to stop.

Later, back at the sawmill Mikey is still struggling to purify tea tree oil. It’s been very tight for all of us. The solvent test of our success, regardless of how hard the cradle was to ‘feed’ is how much gold we have got.

We set ourselves up for the final few pieces of filming. The filming goes well. We have got more gold, even with only an hour or two working the cradle at the river. It’s a cool ending. I shouldn’t have worried too much. Definitely a success.





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