It all started when I was trying to figure out some dates. Well, a lot of dates, actually. I am writing a book called Resilient City: A Timeline of New Orleans History. One of the reasons why I started this project is that the city's tricentennial is in 2018. Another is that I have done so much background research about New Orleans that it would be nice to have it all organized in some kind of chronological fashion so that I can easily locate facts for my family history research. But I digress...
So I decided that because Mardi Gras is such an important part of the city's cultural heritage, that I should figure out the dates and add them to the timeline--the dates of all 300 Mardi Gras celebrations.
That turned out to be easy for the mid-twentieth century on. The New Orleans Public Library has a list of Mardi Gras dates from 1948 forward on their website. Thank you NOPL!
But how was I going to fill in the dates for all the Mardi Gras from 1947 back to 1718? Hmm...I decided it might be easier to locate a list for Ash Wednesdays rather than Mardi Gras, so I googled "historic Ash Wednesday dates" and bam, I found the website called "Easter Dates from 1901 to 2078" by the University of Bamberg in Germany. Danke schoen.
Now I could subtract a day off the Ash Wednesday dates and have my Mardi Gras dates. But that still left 1900 back to 1718. Back to the Google search results. There was the website of the U.S. Navy Astronomical Department. Yes, the U.S. Navy. They have a search box where one can type in a year and receive the dates of its Ash Wednesday and Easter Sunday. And, glory be, it went back to 1583, the beginning of the Gregorian calendar. Semper Fortis.
So then it was a little tedious, because I had to type in the years one at a time into the search box, but then I would be rewarded with the Ash Wednesday date for the year which was easily adjusted to my Mardi Gras date. I was feeling smug--until I hit the first year in which Ash Wednesday fell on March 1. The problem there is that during Leap Year, February has 29 days instead of 28. So then I had to figure out if the particular year I was looking at with the March 1 Ash Wednesday was a leap year or not. How to do that?
This is where my reference librarian training comes in really handy! I knew that I could determine that by using a perpetual calendar, which is a list of different calendar formats which correlates to another list which identifies which calendar format applied to which year. So by consulting the perpetual calendar, I knew when the March 1 Ash Wednesdays had a February 29 Mardi Gras, and which had a February 28 Mardi Gras. Are you with me? So it took a couple hours to work through all 300 years, but eventually I had the correct Mardi Gras dates plugged into the timeline.
Perpetual calendars can also help with other date identification problems. Have you ever run across a document which refers to something happening on a day of the week, but you don't know which date that was? I do, and so find myself turning to the perpetual calendar often for help. They were formerly located only in print almanacs, but now are available online for free.
A little know-how can help us to solve date quandaries in our research, and to record precise dates for events.
