Pardon the length of this reply, but you’ve hit a favorite topic (one of several, fwiw) of mine.
My boss (several bosses ago – back when I was actually working) had this bizarre object on his credenza that he said he got somewhere odd. I don’t remember if it was a gift, an heirloom, something he found at an antique shop or a yard sale, or what. Doesn’t really matter except he was pretty sure it was several hundred years old.
It was maybe three feet tall and looked a little like a paint stirrer in that it had a sort of handle on one end that was rounded, but the majority of its length, the bottom 7/8 or so, was a 7-sided solid. From a distance it looked like a tall cylinder, but up close you could see it was this whatever you call a 7-sided solid, heptagonal?
This stick was attached to a disk that was maybe 4-5" in diameter, so that it sat upright on the credenza. At the bottom of the stick, resting on the disk was a removable disklike object that was cut to fit the seven-sided stick. It had a seven-sided cutout in its center. Like a washer.
The long stick was marked off in a spiraling array of days of the year, starting with March at the top and going through the months until you got to February 29 at the bottom. The removable disk had seven sections (like an orange or grapefruit) marked with the days of the week.
Once a year, on Feb 28 or 29, you would take the removable disk off, give it a 1/7 turn and set it back down on the stick. That gave you the new year’s calendar. Pretty damn slick, I’d say!
It took my knowledge of how calendar reforms had been instituted in Colonial American (as well as European) times for me to be able to explain to him that it used to be that March was the first month of the year, making September, October, November and December the actual 7th-10th months. Before Julius Caesar renamed July, that month had been Quintilis (sp?) or 5th.
But the main beauty of this stick’s layout was that you didn’t have to mess with the weirdness of February right in the middle of things. Being at the bottom, you dealt with the 28 or 29 days thing just when it came time to start the “new year.” You would be trusted to know if the year you were leaving was a Leap Year or not.
Anyway, after all that, my view of the calendar has been that stick ever since I first laid eyes on it.