The McClellan Oscillator is a breadth indicator calculated from the number of advancing issues less the number of declining issues on the New York Stock Exchange Composite Index. The Oscillator (second window, first chart) is calculated by subtracting the 39-day exponential moving average from the 19-day to give you a good idea of trend in market breadth over time.
The second chart, a point and figure chart of the NYSE Composite Index, is really useful in pinpointing key support and resistance levels independent of time.