Fear of trains the social norms of a realistic fear, this anxiety may be classified as a specific phobia about trains. "Campbell's Psychiatric Dictionary" puts fear of trains under the "vehicle phobia", together with fears of boats, airplanes, automobiles, and other forms of transportation. A 1913 short story "Terror" by Jun'ichirō Tanizaki is a first-person narrative of a young man suffering of the morbid fear of travel in trains and streetcars. Tanizaki uses the German word , "railroad sickness". Other travel-related anxieties include: Other transport-related disorders include: Fear of trains The fear of trains is anxiety and fear associated with trains, railways, and
Proof that π is irrational In 1761, Lambert proved that is irrational by first showing that this continued fraction expansion holds: Then Lambert proved that if "x" is non-zero and rational then this expression must be irrational. Since tan(/4) = 1, it follows that /4 is irrational and therefore that is irrational. A simplification of Lambert's proof is given below. This proof uses the characterization of as the smallest positive number whose half is a zero of the cosine function and it actually proves that is irrational. As in many proofs of irrationality, the argument proceeds by reductio ad absurdum. Consider the sequences ("A") and