Early instruments of the type invented by Thomas Alva Edison in 1877, that record and play back sounds using rotating grooved cylinders covered with tinfoil, later made of wax. Although Edison recognized that grooves could also be made on a rotating disc, he concentrated his efforts on cylinders, since the groove on the outside of a rotating cylinder provided a constant velocity to the stylus in the groove. In 1886 vertically modulated engraved recordings using wax coated cylinders were patented by Chichester Bell and Charles Sumner Tainter. Rotating discs were employed in "gramophones," invented in the 1890s.
