From ``$ 3 $'' to ``$ 9 $'' is a difference of 6 hours out of the 12 on the clock, so the hands are separated by $ \frac{6}{12}=\frac{1}{2} $ of the degrees on the clock. From ``$ 2 $'' to ``$ 10 $,'' the smaller angle (clockwise from $ 10 $ to $ 2 $) is a difference of 4 hours out of 12 on the clock, so the hands are separated by $ \frac{4}{12}=\frac{1}{3} $ of the degrees on the clock. The difference in the angles is $ \frac{1}{2}-\frac{1}{3}=\frac{1}{6} $ of the degrees on the clock. Since the clock has $ 360^\circ $, the angle decreases by $ \frac{360}{6}=\boxed{60^\circ} $.