Phonograph "gramophones" or "talking-machines". His "gramophone record" was the first disc record to be offered to the public. They were five inches (12.7 cm) in diameter and recorded on one side only. Seven-inch (17.5 cm) records followed in 1895. Also in 1895 Berliner replaced the hard rubber used to make the discs with a shellac compound. Berliner's early records had poor sound quality, however. Work by Eldridge R. Johnson improved the sound fidelity to a point where it was as good as the cylinder. By 1901, ten-inch (25 cm) records were marketed by Johnson and Berliner's Victor Talking Machine Company, and
Quadratic mean diameter timber in a forest, because it has the practical advantage of being directly related to basal area, which in turn is directly related to volume. QMD can also be calculated as: formula_3 where BA is stand basal area, n is the number of trees, and k is a constant based on measurement units - for BA in ft and DBH in inches, k=0.005454; for BA in m and DBH in cm, k=0.0000785. Quadratic mean diameter In forestry, quadratic mean diameter or QMD is a measure of central tendency which is considered more appropriate than arithmetic mean for characterizing the group