We don’t think about this very much, but as I was looking at some dates related to my philatelic pursuits, it struck me that it was likely that a lot of records wouldn’t have been dated on a Sunday. But how do we know what day of the week any particular date fell on in history? UNIX systems include a utility called “date” in almost all distributions.
To those of you who don’t have UNIX or Linux systems handy, which is the great majority of genealogists that I know, take a look at a site currently called The return of Calendar. Using a cgi script, the site calls the date function on the web server with year numbers dating as far back as 1582. The output is a full year’s calendar in the Gregorian calendar (the calendar that most of the Western world uses today).