Before 1925, all 78s were recorded by means of the artist singing or speakinginto a horn, the power of their voice directly vibrating the recording stylusand thus cutting the wax of the master disc. Collectors call these discs"acoustic" recordings.
Edison's Diamond Discs were available 1910 in 7, 10, 12, 14, 16, and 21 inchformats. They were played at around 78 rpm and contained up to 8 minutesof sound. The disc was made of an early plastic known as Amberol, which "gaveit little surface noise and superb clarity, [but] was incompatible with anyother system. It employed a vertical, rather than lateral cut, groove andcould not be played on any other machine."
Recording and playing speeds ranged from 72 to 86 rpm before the standardsettled at 78 (though Columbia, for example, issued 80 rpm discs for sometime after 1920).
The language of Rule 78 has been amended as part of the general restyling of the Civil Rules to make them more easily understood and to make style and terminology consistent throughout the rules. These changes are intended to be stylistic only.