[Avodah] Birkas haChama

[Zev Sero]

Micha Berger wrote:

> 1- Please stop insisting we used the Julian calendar. Most achronim
> (RMMS excepted) that it would have been assur for chazal to use it --
> violates "hachodesh hazeh lakhem".

The fact is that people who interact with goyim have always had to
be aware of those goyim's calendar.

 
> Rather, Shemu'el happened to use the same 365-1/4 estimate that the
> Romans did. It's a logical enough estimate. Common cause with the Julian
> calendar, not ancestry from it.

For those who are going to calculate it themselves, cheshbon R Ada
is almost as easy.  The advantage of cheshbon Shmuel is that you
don't need to calculate it, you just need to look at a goyishe
calendar, or ask a goy what date it is.  Which is why the date for
switching to Tal Umatar, which each person needs to determine for
himself, follows cheshbon Shmuel.  Most people can't be expected
to make the calculation themselves, so it would be unreasonable for
the minhag to depend on them doing so.  Determining the keviut of
Rosh Hashana is not given to each person; even with no communication
and no printed calendars, only one person per community has to
perform the calculation, and so it uses the more complicated (though
still inaccurate) cheshbon R Ada.  A more accurate calculation than
R Ada's would have made it still more complicated, enough that there
might not be anyone in a community capable of it, so no such scheme
was ever attempted.  (That's assuming Hillel's Sanhedrin realised
that R Ada's calculation wasn't accurate.)


> 2- Tequfas Shemu'el is simply an approximation to the nearest 5 digits
> for computing the March Equinox. And birkhas hachamah IS when that
> approximate date is on Wed.

No, because that would happen on average every 7 years, not exactly
every 28.  The 28-year cycle is an artefact not of the 365.25 day
calculation, but of a human-constructed calendar *based* on that
calculation.

Again, though, my main question is why we don't say Birkat Hachama
every year.

-- 
Zev Sero               Something has gone seriously awry with this Court's
zev at sero.name          interpretation of the Constitution.
                       	                          - Clarence Thomas