Despite the scientific evidence indicating that masturbation is generally a normal variant of sexual expression and that it does not seem to have a causal relationship with sexual pathology, negative attitudes about masturbation persist and it remains stigmatized. That is, a difference in mortality appeared between any two subjects when one subject ejaculated at around two times per week more than the other. Retrieved 7 August The publication of Kinsey's and Masters and Johnson's research revealed that masturbation was both common and harmless. In the s, Havelock Ellis reported that turn-of-the-century seamstresses using treadle-operated sewing machines could achieve orgasm by sitting near the edge of their chairs. A variation on this is to place the fingers and thumb on the penis as if playing a flute, and then shuttle them back and forth.