Herbert Newton Casson, The History of the Telephone
“ To give the most efficient service, there will always need to be an expert to stand between it and the public. As the final result of all these varying changes in switchboards and signals and batteries, there grew up the modern Telephone Exchange. This is the solar plexus of the telephone body. It is the vital spot. It is the home of the switchboard. It is not any one's invention, as the telephone was. It is a growing mechanism that is not yet finished, and may never be; but it has already evolved far enough to be one of the wonders of the electrical world. ”
