When a wind-up phonograph is manually wound up with a crank, the record spins and the needle vibrates, causing sounds that are then amplified by a horn. The record transfers the recorded sound to the needle through the shape of the groove in the record. This type of gramophone can operate entirely without electricity, as few homes in the early 20th century, when these gramophones were popular, had electric power.
To get sufficient sound volume without the use of loudspeakers, the record revolves at quite a high speed; the groove is coarse, and the needle is pressed hard against the surface. As a result, needles wear out often and have to be frequently replaced. Furthermore, this type of record can store only about two and a half minutes of music on each side, which is why hit songs from that time period tended to be short.
The standard speed for such records is 78 rpm, which is why the records are commonly called "78s." A clockwork regulator maintains constant revolution speed throughout the 20 to 30 minutes that the turntable typically spins until it's necessary to wind up the motor again.
The phonograph was a large improvement over the earlier technology of storing sound on wax cylinders, as records were much easier to mass produce. The wind-up phonograph was made obsolete by gramophones using electric motors and sound amplification.