Martinville's first patent described a flat recording surface and a weight-driven clockwork motor, but the later and more familiar form of his invention, marketed by Rudolph Koenig in 1859, recorded on a sheet of lampblack-coated paper wrapped around a cylinder which was hand-cranked. The cylinder was carried on a coarsely threaded rod so that it progressed along its axis as it rotated, producing a helical tracing. The length of the recording that could be accommodated depended on the speed of rotation, which had to be rapid in order to resolve the individual waveforms of various sounds with good detail. If only longer-term dynamics such as the cadences of speech were being studied, the cylinder could be rotated much more slowly and a longer recording could be made. Some phonautographs included a tuning fork or other means of simultaneously recording a known reference frequency.