November 21 is the day that the settlers in Plymouth Colony signed the Mayflower Compact in 1620. Except that if you’d asked them at the time what day it was, they would have said it was November 11 — because it was. It didn’t become November 21 until 1752, when the old calendar was finally ditched in favor of the Julian calendar. The calendars were off by about 10 days at that point, so today is the anniversary of the Mayflower Compact because of that adjustment.
The calendar situation is ridiculously complicated — and as an aside, if you’d asked the colonists whether, since it was November, they were looking forward to New Year’s Day, they would have said “what are you talking about; that’s not for months.” That’s because January 1 wasn’t the start of the year then. Their year started on Lady Day, which is March 25. Except that obviously it isn’t that simple to just say “Lady Day is March 25;” it all depends. And in the case of Lady Day, it gets even worse, because when they changed the calendar, they changed the start of the year, but Lady Day wasn’t adjusted in all cases. That is, Lady Day used to be New Years Day, and it was on March 25 in the old calendar, so in the new calendar it should have been moved to April 6 — and it was, but lots of people were so used to Lady Day being on March 25 that they just left it there. So then there were two. Anyway, the April 6 date became, hilariously, Old Lady Day even though old ladies didn’t get anything out of it (which doesn’t seem very fair). It’s still the start of the tax year in the UK.
Another question the Plymouth colonists would have thought absurd is “what’s the temperature?” It would seem like a natural concern, especially since they were heading into a pretty difficult winter in a part of the world with a much more extreme climate than they were used to. But they wouldn’t have understood the question because the idea of a temperature scale hadn’t occurred to anyone yet. That wouldn’t happen until 1701, when Ole Rømer, a Danish astronomer, came up with it. He quite reasonably based his scale on water and set the freezing point of pure water to…no, of course it wasn’t zero degrees; what were you thinking? In the Rømer scale, water freezes at 7.5°. So naturally the point at which water boils is the other end of the scale, so he set that to…wait for it…60 degrees. The zero point on the scale, by the way, represents the temperature where seawater freezes. At least the seawater with the specific degree of salinity nearest wherever Rømer took a sample.
Nobody uses the Rømer temperature scale any more, but having a scale was his idea. He was very interested in measuring things, and on November 21, 1676, he presented the results of a study he had made measuring, of all things, the speed of light. Most people at the time thought light traveled at an infinite speed. But Rømer was an astronomer, and used to dealing with distances and values enormously greater than most people encountered. And he was right that light had a speed. He didn’t come up with the value we use today, but it was a start.
The speed of sound is much easier to calculate, partly because noticing that it has a limited speed is a common everyday experience. In addition to speed, of course, sound has other qualities like tone and pitch and volume. These are all based on vibration, which is something Thomas Edison made use of when he invented the phonograph — which he announced on November 21, 1877. It wasn’t the first device that was able to record sound — those went back 70 years earlier, to Thomas Young’s method of tracing the vibrations of sounds — but it was the first to be able to play back the sound it recorded. In between there were machines like the “phonautograph,” which recorded sound as a tracing on paper. Without a way to play the sound back, though, they were just curiosities. Some of the original phonautograph tracings are still around, though, and nowadays they can be played back, using an optical scanner and a computer. So if you want to, you can listen to a couple of French songs recorded in 1860.
Temperature scales, the speed of light, and the vibration of sound aren’t the only scientific points of interest along the November 21 highway. This is also the day that Albert Einstein published his famous 1905 paper that led to the even more famous “E=mc^2” formula. And speaking of highways, in 1942 the Alaska Highway was finished on November 21, 1942 — probably just in time for nobody to use it because it was covered in snow.
Being covered in snow wasn’t a problem for the La Ronde restaurant when it opened on November 21, 1961, in Honolulu. It wouldn’t normally be worth noting that another restaurant opened, even if it was in Honolulu. But La Ronde, built on top of the Ala Moana Office Building, was the first revolving restaurant in the US. It revolved at the dizzying speed of once per hour. Although nobody seems to have made a single note about the food at La Ronde, the rotation was popular enough that before long rotating restaurants were opening in many cities around the US, and practically all of them revolved at the same once-per-hour rate. New York has had two (only one is still open), but since they were built in 1976 and 1985, they didn’t offer a panoramic view of opening of the Verrazano-Narrows bridge. That happened in 1964 — on November 21, in fact.
The bridge was opened just in time to accommodate everyone traveling for Thanksgiving — which, as you know, goes back to the same Plymouth colonists that signed the Mayflower Compact so many years ago today. There’s very little in the modern stories of Plymouth and Thanksgiving that’s true, and the time they inhabited would be pretty alien to us. But if you asked that question about the temperature in a way they understood, they would certainly have been been able to give you an answer: it was cold!
