Alfred Cowles' (1934) test of the Dow Theory apparently provided strong evidence against the ability of Wall Street's most famous chartist to forecast the stock market. In this paper, we review Cowles' evidence and find that it supports the contrary conclusion -- that the Dow Theory, as applied by its major practitioner, William Peter Hamilton over the period 1902 to 1929, yielded positive risk-adjusted returns. A re-analysis of the Hamilton editorials suggests that his timing strategies yield high Sharpe ratios and positive alphas. Neural net modeling to replicate Hamilton's market calls provides interesting insight into the nature and content of the Dow Theory. This allows us to examine the properties of the Dow Theory itself out-of-sample.