Let’s be clear about this. The origin of the phrase “saved by the bell” is not that people feared being buried alive during the Black Death and that they therefore had bells fitted outside their coffins with a string inside as a means of warning should they revive after burial.
There is no doubt that the possibility of being buried before death was greater in the 17th century than it is today, so much so that there were genuine fears held by famous persons in those days of that happening:
"All I desire for my own burial is not to be buried alive."
- Lord Chesterfield, 1769.
"Have me decently buried, but do not let my body be put into a vault in less than two days after I am dead."
- deathbed request of George Washington.
"Swear to make them cut me open, so that I won't be buried alive."
- Frederic Chopin's last words.
Several designs for coffins with warning devices, known as safety coffins, have been patented:
Thomas Pursell’s 1930s-era tomb that featured doors that could be opened from the inside.
The phrase "saved by the bell", however, comes not from being buried alive but from the world of boxing where a boxer is saved from losing the bout by the round coming to an end, signified by the ringing of the bell. Its first recorded use is from a Massachusetts newspaper The Fitchburg Daily Sentinel, February 1893: "Martin Flaherty defeated Bobby Burns in 32 rounds by a complete knockout. Half a dozen times Flaherty was saved by the bell in the earlier rounds."
For the same reason, the notion sometimes touted in emails that a dead ringer was a person who had been saved from being buried alive by the ringing the bell fitted inside a coffin is likewise incorrect.
Whilst a ringer in Australian slang is the fastest shearer in the shearing shed (“The ringer looks around but he’s beaten by a blow” - lyric, Click Go the Shears), in the present context the term originally referred to a horse substituted for another so as to fool the bookmakers. From there it has extended to other things that resemble something else, close duplicates.
The expression “dead ringer” simply means a very close duplicate, almost indistinguishable from the other, much like the term “dead” is added to words to make “dead shot”, “dead certainty” and “dead heat”.
Which leads me to an oldie but a goodie…
After Quasimodo's death, the bishop of the Cathedral of Notre Dame sent a message through the streets of Paris that a new bell ringer was needed. The bishop decided that he would conduct the interviews personally and went up into the belfry to begin the screening process. After observing several applicants demonstrate their skills, he had decided to call it a day when an armless man approached him and announced that he was there to apply for the bell ringer's job. The bishop was incredulous. "You have no arms!"
"No matter." said the man, "Observe!" And he began striking the bells with his face, producing a beautiful melody on the carillon. The bishop listened in astonishment, convinced he had finally found a suitable replacement for Quasimodo. But suddenly, rushing forward to strike a bell, the armless tripped and plunged headlong out of the belfry window to his death in the street below. The stunned bishop rushed to his side. When he reached the street, a crowd had gathered around the fallen figure, drawn by the beautiful music they had heard only moments before. As they silently parted to let the bishop through, one of them asked, "Bishop, who was this man?" "I don't know his name," the bishop sadly replied, "but his face rings a bell."
(Wait, there’s more)…
The following day, despite the sadness that weighed heavily on his heart due to the unfortunate death of the armless campanologist, the bishop continued his interviews for the bell ringer of Notre Dame. The first man to approach him said, "Your Excellency, I am the brother of the poor armless wretch who fell to his death from this very belfry yesterday. I pray that you honour his life by allowing me to replace him in this duty." The bishop agreed to give the man an audition, and, as the armless man's brother stooped to pick up a mallet to strike the first bell, he groaned, clutched at his chest and died on the spot.
Two monks, hearing the bishop's cries of grief at this second tragedy, rushed up the stairs to his side. "What has happened? Who is this man?" the first monk asked breathlessly. "I don't know his name," sighed the distraught bishop, "but he's a dead ringer for his brother."