Freud (Drei Abhandlungen zur Sexualtheorie, p. 118) refers to the sexual pleasure of swinging. Swinging another person may be a source of voluptuous excitement, and one of the 600 forms of sexual pleasure enumerated in De Sade's Les 120 Journées de Sodome is (according to Dühren) to propel a girl vigorously in a swing.
The fact that horse exercise may produce pollutions was well recognized by Catholic theologians, and Sanchez states that this fact need not be made a reason for traveling on foot. Rolfincius, in 1667, pointed out that horse-riding, in those unaccustomed to it, may lead to nocturnal pollutions. Rohleder (Die Masturbation, pp. 133-134) brings together evidence regarding the influence of horse exercise in producing sexual excitement.
A correspondent, to whom the idea was presented for the first time, wrote: "Henceforward I shall know to what I must attribute the bliss—almost the beatitude—I so often have experienced after traveling for four or five hours in a train." Penta mentions the case of a young girl who first experienced sexual desire at the age of twelve, after a railway journey.
Langdon Down, British Medical Journal, January 12, 1867.