The first recording of sound was made and reproduced by Thomas A. Edison in 1877. Although his reproduction of Mary Had a Little Lamb was quite primitive, it was a milestone. Little did Edison know that he was paving the way for a new and exciting industry. Edison's wax cylinders became obsolete before long, as they were inconvenient and (as collectors know) very breakable!
Emile Berliner, an American inventor, demonstrated his Gramophone machine in 1888. This was the first machine to make recordings on a flat, not cylindrical, disc. Early recordings were made acoustically, that is, with a person speaking or singing very loudly into a megaphone which would agitate a diaphragm. The vibrations would then be transferred to a stylus which would cut grooves into the record. After being cut, the record could be played back by the same stylus, vibrating the diaphragm and producing sound through the megaphone. Volume was very limited and sound quality was considerably poor. Vacuum tubes and electronic techniques of the 1920's led to much more accurate cutting methods and the traditional method was scrapped.
In 1948 the long-playing microgroove record was introduced, designed to be played at 33 1/3 revolutions per minute, much slower than the then-standard 78 rpm disc. Soon thereafter the 45 rpm disc was developed. The 33 1/3 speed was used for recording classical music and spoken recordings, whereas the 45 speed was used for recordings in the pop field because of its more convenient size.
Disc recording requires the use of a flat aluminum disc coated with a lacquer. The disc is spun at the correct speed and a sharp cutting tool cuts a V-shaped groove in the coating. The stylus travels across the surface of the disc, oscillating from side to side with the correct frequency and amplitude to reproduce the sound being recorded. The walls of the groove resemble a wavy pattern (see figure below). Modern recording employs the use of an electrical signal electromagnetically driving the cutting head to form the groove.