Did you notice anything different about September 1752?  If not, check out following calendar.  You computer running windows will only show calendar from 1980.  You have to see it on either Linux or UNIX running server.  Check more at http://en.wikipedia.org/wiki/1752

$ cal 9 1752

   September 1752
 S  M Tu  W Th  F  S
             1  2 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30