今天的狗儿涂鸦是傅科摆（Foucault’s Pendulum），纪念傅老师194岁生日。那个摆不用说了，但令摆那么“摆”的那只看不见的手应该夸奖一番：地球自转产生的Coriolis力。河流的弯曲和大气的湍流，都与那只手的舞动有关…… 

《玫瑰的名字》的作者Umberto Eco写过一本同名的书Foucault’s Pendulum，开头讲那个摆，有段有趣的文字（英译）： 

I knew -- but anyone could have sensed it in the magic of that serene breathing -- that the period was governed by the square root of the length of the wire and by pi, that number which, however irrational to sublunar minds, through a higher rationality binds the circumference and diameter of all possible circles. The time it took the sphere to swing from end to end was determined by an arcane conspiracy between the most timeless of measures: the singularity of the point of suspension, the duality of the plane's dimensions, the triadic beginning of pi, the secret quadratic nature of the root, and the unnumbered perfection of the circle itself.

   这里面特别有趣的是无理与有理的对比，还有几个数字的排比：零维的点，2维的面，3打头的π，平方的根……从小说里看到这样的东西比在博物馆里看到那个摆，更令人激动——因为它看到了摆后面的东西……