Vibrator (sensual)
The electrically powered vibrator was invented in the 1880s by doctors, who were treating women for "hysteria" for centuries by performing what today would be considered masturbation. At the time, however, not only did doctors regard the "vulvular stimulation" as having nothing to do with sex, they reportedly found that it took a lot of time to do and it was hard work. The vibrator did it more quickly and easily, and because of this it was very popular with doctors.