[Avodah] Birkat Hachamah

[Zev Sero]

Galsaba at aol.com wrote:
> I am curious to know what is the first source about saying Birkhat 
> Hachama on April 8 (Greorian Calendar) which is March 3rd (Julian 
> Calendar).

No, it's March 26.  The difference between Julian and Gregorian is
13 days.


> If I try to calculate by Tekufot, I do not get the same date.
> If we say Tal Umatar 60 days after the tekufa, then the tekufa (tekufat 
> Tishrei) is Dec 4th minus 60, whcih gives us - October 6th. To those 
> that count just 59 less (if 60 days after Tekufa includes the day of the 
> tekufa, and the 60th day), then Dec 4th - 59 = October 7th.  Tekufat 
> Nissan is 1/2 year later, which is October 7th + 365.25 / 2 = April 6th. 
> I am still missing two days here, as Birkat Hachama is April 8.

Tekufat Tishri, according to cheshbon Shmuel, is always on 24-Sep Julian,
or 7-Oct Gregorian.  Last year it was at 0300, this year it will be at
0900, next year it will be at 1500, and in 2011 it will be at 2100.
We start saying Tal Umatar at Maariv of the 60th Jewish day; this year
7-Oct will be 19 Tishri, so the 60th day will be 18 Kislev, which is
5-Nov, so we start at Maariv of that day, i.e. on 4-Nov.  In 2011, 7-Oct
will be Erev Yom Kippur, but the tekufah will be at 2100, so it will
already be Yom Kippur, so the 60th day will be 10 Kislev, or 6-Dec, and
so we will start Tal Umatar at Maariv on 5-Dec.

Tekufat Nissan this year be on Tuesday 25-Mar (7-Apr Gregorian) at 1800,
i.e. the very beginning of Yom Revi'i, just as it was, according to this
cheshbon, at the creation, and just as it is every 28 years.  We say the
bracha on Wednesday morning, 8-Apr.


-- 
Zev Sero                    A mathematician is a device for turning coffee
zev at sero.name               into theorems.                   - Paul Erdos