Russian Calendar

This was submitted to me and covers a question that I've also had, so I thought it would be of use to many of you.
It concerns a question about the difference in dates in Russia vs. the US prior to the Russian Revolution.

Russia was still on the Julian Calendar until 1918.  When Russia converted
to the Gregorian calendar, they skipped 13 days - one day it was the 31st of
January 1918, and the next day it was 14th of February 1918.

During the 1800s, the difference was 12 days.  So, if it was 7 April 1874 in
Russia, it was 19 Apr 1874 here in the US and in Western Europe.

In the Frank baptism records, we see groups of baptisms occurring on the
same day, for example 12 infants being baptized on 17 Aug 1858, and 8
infants being baptized on 24 Aug 1858.   If I look up what day of the week
that was, it is Tuesday.  Initially I thought that's odd, why would they do
all of the baptisms on Tuesday?  Then I realized that 17 Aug 1858 (Julian
Calendar) is actually 29 Aug 1858 (Gregorian calendar).   29 Aug 1858 was a
Sunday.   That makes more sense.

I am pretty sure that when the calendar conversion happened, they didn't
skip any days of the week.  In other words, if it was Sunday in Russia, it
was Sunday in Western Europe.  I just can't find anything online that
specifically states that is the case.

Maggie Hein