Question

The passage below is adapted from an essay on the history of sound recording.

In the late nineteenth century, the quest to capture and preserve sound transformed the landscape of human communication. Before this era, music, speech, and performance were ephemeral, surviving only in memory or through written transcriptions. The invention that shattered this limitation was the phonograph, conceived by Thomas Alva Edison in the autumn of 1877. Edison’s breakthrough occurred while he was working on improvements to the telegraph and telephone. He realized that the vibrations of the human voice could be used to indent a moving medium, which could then be replayed by tracing a needle along the same grooves.

Edison’s first prototype utilized a sheet of tinfoil wrapped around a hand-cranked grooved metal cylinder. To record sound, a speaker shouted into a mouthpiece, causing a diaphragm to vibrate. This vibration drove a sharp stylus into the tinfoil, leaving varying indentations. To play back the recording, the stylus was returned to the starting point, and as the cylinder rotated, the stylus followed the indentations, vibrating the diaphragm and reproducing the sound. The first recorded words were Edison’s own recital of 'Mary Had a Little Lamb.' While the device was a marvel, the tinfoil was fragile and degraded after only a few playbacks, making the original phonograph little more than a novelty.

Recognizing the limitations of tinfoil, other inventors sought to improve upon Edison’s design. In the early 1880s, Chichester Bell and Charles Sumner Tainter, working at the Volta Laboratory established by Alexander Graham Bell, introduced the graphophone. Unlike Edison’s machine, which used tinfoil on a metal cylinder, the graphophone recorded onto wax-coated cardboard cylinders. The wax was soft enough to be easily engraved by a cutting stylus, yet durable enough to withstand repeated playback without significant degradation of sound quality. This shift from indenting tinfoil to engraving wax marked a major technological advancement, turning sound recording into a commercially viable enterprise.

Shortly thereafter, Emile Berliner introduced another radical departure from Edison's design: the gramophone. Patented in 1887, the gramophone abandoned cylinders entirely in favor of flat zinc discs coated with beeswax. Rather than employing a vertical 'hill-and-dale' engraving method, where the stylus moved up and down to cut grooves of varying depths, Berliner used a lateral-cut method, where the stylus moved from side to side in a groove of constant depth. This lateral recording technique was easier to replicate on a mass scale. Berliner developed a process to electroplate the original zinc disc to create a metal stamper, which could then press duplicate discs into hard rubber (and later, shellac). This ability to mass-produce recordings from a single master disc laid the groundwork for the modern music industry.

Despite these competing designs, Edison did not abandon his invention. In 1887, he returned to sound recording and introduced the 'Perfected Phonograph,' which utilized solid wax cylinders instead of tinfoil. This design allowed users to shave off the outer layer of a recorded cylinder to reuse it for a new recording. The battle between cylinders and discs continued for decades, but by the 1920s, the flat disc format championed by Berliner had largely triumphed due to its ease of storage and superior mass-production capabilities.

According to the passage, which material did Chichester Bell and Charles Sumner Tainter use to record sound on the graphophone?