 With the two object balls stacked perpendicular to a rail and just next to it, the rub nurse is performed by gently banking the cue ball off the rail just before them resulting in a soft graze of both and the same or near the same position repeating.By the late 1870s, the newer discipline of balkline increasingly becoming effective at limited nursing.It eclipsed one-cushion caroms as the game of public match play and tournaments until well into the 20th century.