Here's the thing about September 10, 1752. It didn't exist. In fact, as far as the UK and its colonies were concerned (this included what later became the US), there was no September 3 through 13 at all.
Interestingly enough, Siri will respond with curiously named days for several of those missing dates including Prophet Sabalan's day, which appears to be a Druze holiday.
Siri does not always provide the most historically accurate date associations. For example, ask it "Which day of the week was July 4, 1775?" or "Which day of the week was December 7, 1940?" or even (getting back to 1752) "Which day of the week was September 4, 1752?"
Steven Sande and Erica Sadun have been working on the third edition of Talking to Siri, the book that covers all the ins and outs of everyone's favorite digital assistant.http://en.wikipedia.org/wiki/Gregorian_calendar