When this site first came on line many years ago, we introduced it with this explanation:
Dear friends and gentle hearts,
Language speaks to the mind, but music speaks straight to the soul. Yet music, like other arts, is subject to the arbitrary tyrannies of fashion. Much that is thrilling and beautiful has been utterly forgotten. But it lives on in these recordings, which sit neglected in flea markets and junk shops until someone comes along and says, “I’ll give you five dollars for that whole box.”
“The lateral cut” is the method of inscribing sound vibrations in these records. The earliest recordings were made with a vertical or “hill-and-dale” cut, in which the needle vibrates up and down in the groove. But Mr. Emile Berliner invented a “lateral-cut” system in which the needle vibrated side to side, and that system eventually became the standard for phonograph records. There is no guarantee that absolutely no vertical-cut recordings will ever appear on this site, in spite of its name, but almost all the records here will be lateral-cut records.
There were a few words about the ambiguous nature of sound copyright in the United States, which happily is no longer ambiguous. Everything from before 1923 is in the public domain, and so we are rebuilding the collection from purely public-domain recordings.
All of these recordings were made by the acoustical process, the only process in commercial use until 1925. The sound was collected by a big horn, and the vibrations were transmitted mechanically to the cutting needle. Although acoustical records do not preserve the full frequency range the way electrical recordings do—that is, recordings made with a microphone—it’s surprising how much of the original sound is preserved in those grooves if you know where to look for it. We have put most of these records through what we call an “artificial electrification” process, meaning that we have tried to revive the frequencies that are usually almost inaudible in acoustical recordings.
Since all these recordings are in the public domain, you can do anything you like with them. We claim no property rights in the restored versions. The text on this site is also released into the public domain under a Creative Commons CC0 public-domain dedication.
The Lateral Cut 
“Language speaks to the mind, but music speaks straight to the soul.”
Echoes of your Johnnie thesis?
Harry Bradshaw, who works at the Traditional Music Archive in Dublin as an employee of RTE, developed a system for getting the most remaining fidelity out of old 78 rpm records –
As a 78 (or 45 or 33) rpm record plays, the needle, as it skates along the groove, puts more pressure on the outside wall of the groove than on the inside. This is what propels the needle and arm inward as the recording plays. The outside groove thus gets more wear with repeated plays.
Harry rigged up an old 78 player to play backwards. I think he simply reversed the polarity of the motor that spins the turntable. The needle starts in the center of the record and works its way outward, with more pressure on the better preserved inner wall of the groove.
He captures the signal on an old monoaural tape recorder, then simply plays the tape backward to reproduce the original sound. With this method, he has produced several compilations of famous older players for whom we are fortunate enough to have a recorded output.
His other assignment, for which he has been assigned space at the Archive, has been to remaster to digital and catalog all the old acetate archive tapes of RTE traditional music broadcasts from the 50s through the 70s. They will be available for research use at the Archive. There were some 30,000 numbers to remaster at the start of his project, some 10-15 years ago, but he may be done with that project now. Haven’t talked to him in some 7-8 years.