I'm trying to wire up this circuit

http://www.circuitstoday.com/audio-oscillator-circuit-2

But I don't understand how I can create the negative rail in practice.

I know one way of creating a dual polarity supply is by connecting two batteries in series and taking ground from the mid point...but in this circuit there is no ground connection, so all that would happen is that the connections to -10V would actually just be ground and the +10v would be efectively 20V?

Sorry if this is stupid. Could anyone explain how I would physically create a battery supply to drive this circuit?

Thanks

 

My best guess is that the output waveforms will be taken with reference to ground '0' volts .
You will need a dual power supply + and - 10 for this to work I think , the only diffrence is when you will take your output terminal , you will reference the ground to the '0' volts ground , not to the -10 volts.
You can make a simple dual supply out of 2 batteries in series .
If you want to make a dual supply out of a single supply like a wall-wart or something then I can provide a schematic

 

I think your are right:

connecting two batteries in series and taking ground from the mid point

, +10V connects to +10V, -10V connects to -10V, your output is pin9 to gnd/ pin3 to gnd/ pin2 to gnd.