Bill David,
That is a fairly standard differential amplifier circuit. You can look at nearly any basic electronics text to find a description of that or a similar circuit.
Fundamentally, the current through R1 is approximately constant. That current is split between the two transistors in proportion to their base voltages. If the voltage at input 1 is more positive than the voltage at input 2, then the current in Q1 increases and the current in Q2 decreases. A decrease in Q2 collector current produces a smaller voltage drop across the collecter resistor Rc(2) and the output voltage rises toward Vcc.
Lynn
