Speed.

As a cause for derailment one should be very careful in hastily adopting this theory, for:

(1) Experienced railwaymen are invariably unable to judge speed correctly.

(2) The capacity for speed of engines is not properly understood by most people.

Beaton says that the relation of speed to the condition of the track cannot be reduced to a formula. Also that elimination of sharp curvature and steep gradients will enable considerable increases in speeds to be made, and that, if it were practicable to increase the radius of all curves to 25 chains no speed restriction would be necessary for curvature. Beaton even goes so far as to say—and I am fully in agreement with him—that lateral vibration decreases with high speeds, while the vertical vibration due to “slacks” or low joints has a much less magnitude of range at high than at low speeds.