Brendan Hanley (leading), Stephanie Clegg, Se?n Tidey, Milo Deane (guest); callout: Rachel Sparrow
This was originally intended as a solo route-finding and poke-about, but then I invited Milo, the teenage son of my long-distance walking companion Bay Deane to join me, and then I decided it would be churlish not to advertise the trip on the club?s Google Group, so Steph and Se?n came along, too.
It was Steph?s and Se?n?s first trip to Goatchurch Cavern, believe it or not.
The four of us followed the usual route via the Giants Stairs to Drunkard?s Gallery and then through Bloody Tight to the Terrace, then the route-finding and poking about began as we split into two teams (me and Milo, Steph and Se?n) to find our way to the Dining Room and the foot of the Coal Chute.
The way to the Boulder Chamber was marked by Milo slipping through the two tubular squeezes and then working his way back towards the rest of us as we negotiated the tight rift on the extreme left of the various routes to the Boulder Chamber. No-one got stuck.
I showed the impossibly small hole in the floor through which Danielle Gorman, Tricia Denning-Kendall (and possibly others) have passed into the Water Chamber below, then I rigged a hand-line and we took the more conventional, larger route down Jacob?s Ladder instead.
In the Water Chamber we had a look at where the stream enters and then leaves the chamber, and then at the little waterfall under the Water Chamber. By then it was time for Steph and Se?n to leave for the afternoon trip to sump 1 of Swildon?s Hole, so we made a mad dash via the Coffin Lid to the top of the Pixie Steps so that Steph and Se?n could find their way out safely, then Milo and I went back down via the Coffin Lid Bypass to the Drainpipe.
Remembering how I had flunked my first attempt at the Drainpipe and had to be coaxed by the infinitely patient Andy Hebden on my second, successful, attempt, I was prepared to be really supportive of young Milo at this juncture, but when I had finished my rather laboured description of the Drainpipe and ways of moving through it, he cheerily asked me if he could go first, so off he went, completely untroubled.
In the car on the way to the trip, Milo and I had discussed the possible acoustic properties of the Drainpipe, so as he neared the chamber at the end, the experimenting began. The first experiment was to create a single toneless boom to see what would happen: Milo thwacked the side of the Drainpipe with his leg, and we both listened to the echo from way behind us. It was rather spooky.
We left it there for a few minutes while we played about in the chamber at the end, trying out total darkness, and then trying out two sensory experiments in the darkness.
We waved our hands in front of our faces, which produced ghostly images in our minds? eye, the result of body telemetry displaying the hand?s position to the conscious mind.
We wanted to find out if we have any rudimentary echo-location facility. We used out voices to make short tone bursts, and listened to the sound coming back off the chamber walls. Of course, we had already seen the shape of the chamber before turning off our lights, so it was not a proper scientific test of anything, but there did seem to be a sense coming to us of the shape of the chamber around us.
Back in the Drainpipe, we experimented with trying to make the column of air to resonate, using our voices. We were easily able to make it resonate across its width by stimulating it with specific notes within the normal singing range of a bass voice ? it was uncanny to hear our voices amplified and confined in the tube. However, we were unable to make it resonate along its length, as neither of us can sing low enough ? I can just reach a C# two octaves below middle C (about 70Hz), but the fundamental resonant frequency is probably about 2? octaves lower than this, somewhere around G six octaves below middle C (about 12Hz) which is too low to sing and too low to hear as a note.
When I was about half way along, and Milo was a few feet behind me, we turned out our lights again and lay in the darkness, something I had not done before in the Drainpipe. I felt less aware of the smallness of my surroundings, and quite comfortable (psychologically, I mean) and relaxed.
On the way out, Milo shimmied up Jacob?s Latter like a monkey, but I went up the Coffin Lid Bypass. We were able to spend ten minutes poking about in the Maze, and moved so far across and up that we must have been really close to the entrance gallery, but we could not find a way through. We left the Maze via the crawl that leads back towards Drunkard?s Gallery, then left the cave free climbing via the Tradesman?s Entrance.
Congratulations to Milo for moving about underground like an already-experienced caver, and for negotiating the Drainpipe with panache.
I am planning more experiments in the Drainpipe. I hope use drums for toneless pulses, human voices in dissonance to produce a 12Hz heterodyne (beat), and, if I can lay my hands on them, a set of bellows and a reed from an old organ pipe.
The Drainpipe resonance calculations are based on an 9?C air temperature, a 40? length, and the tube behaving as if open at both ends.
http://hyperphysics.phy-astr.gsu.edu/hbase/waves/opecol.html
http://www.phys.unsw.edu.au/jw/notes.html