First Experiment: An analog breadboard computer

For my first experiment, I will build a computer.  No, not a supercomputer, not a desktop, not even a netbook.  It is a computer that can only do one mathematical operation: averaging three quantities together.  With the schematic setup below and when the voltmeter is connected to the circuit at the point shown in the schematic and illustrations, it should register the algebraic average of the three batteries' voltages:

Why is this called a computer?  From the expirement website:

The sheer simplicity of this circuit deters most people from calling it a "computer," but it undeniably performs the mathematical function of averaging. Not only does it perform this function, but it performs it much faster than any modern digital computer can! Digital computers, such as personal computers (PCs) and pushbutton calculators, perform mathematical operations in a series of discrete steps. Analog computers perform calculations in continuous fashion, exploiting Ohm's and Kirchhoff's Laws for an arithmetic purpose, the "answer" computed as fast as voltage propagates through the circuit (ideally, at the speed of light!)...Digital computers enjoy the advantage of performing mathematical operations with much better precision than analog computers, albeit at much slower theoretical speeds. 

This analog computer will do nothing more than proving network theorems and equivalent circuits.  Regardless, it is a start, and all that will be needed for purchase is a breadboard, which will cost between $4 and $10, opening the doors for future experiments like NAND logic gates, Amplifier Circuits, and 1 bit memory modules.