Volume 15 Number 60
                       Produced: Sun Oct  9  1:03:47 1994

Subjects Discussed In This Issue: 

19 year cycle
         [Danny Skaist]
19th birthday
         [Dena Landowne-Bailey]
19th birthdays
         [Rivka Goldfinger]
Calendar Issues: Molad, Leap Months, Equinox
         [Jonathan Baker]
Onaah and Interest-taking
         [Jeff Mandin]
When do 19th birthdays coincide?
         ["Ilene  M. Miller"]


From: DANNY%<ILNCRD@...> (Danny Skaist)
Date: Tue, 4 Oct 94 13:23 IST
Subject: 19 year cycle

>-Alan Mizrahi
>will coincide.  I have heard of cases where after 19 years the calendars
>were off by a day.  Does anyone know why that happens?

The question was "why doesn't it always coincide" and the answer is that
we don't wan't it to and so we don't permit it to.

The day of the week of any given date moves forward 3 days (2 days just
following a secular leap year) every 19 years.  If the 15th of Nissan
would always coincide with the same "secular" date every 19 years, then
Pessach will eventually fall out on a day that we don't want it to (b"du
i.e. Mon, Wed, Fri) so we fix our calander to avoid the problem.



From: Dena Landowne-Bailey <dena_landowne-bailey@...>
Date: Wed, 05 Oct 94 14:25:45 EDT
Subject: Re: 19th birthday

In response to Alan Mizrahi's question about the 19th
birthday (and 38, etc.) lining up on the solar & lunar
calendars, I always thought that it had something to do with
I was born Feb 21st, on a leap year, my 19th birthday(s)
didn't line up, and I always blamed it on that (but I have
no scientific evidence).
Check if the other people whose dates were off were born in
leap years...maybe we can _prove_ this.
                                     Dena Landowne Bailey


From: <RGOLDFINGER@...> (Rivka Goldfinger)
Date: Tue, 04 Oct 1994 07:22:00 -0500 (EST)
Subject: 19th birthdays

Alan Mizrachi asks why on occasion a person's Hebrew and English
nineteenth birthdays will be off by a day.  I always assumed this to be
due to the difference in what we call a day vs. what the rest of the
world calls a day.  If a person was born after Shekia (sunset), but
before midnight, his English birthday would be the previous day, while
his Hebrew birthday would be the new day. (Or maybe this is only after
Tzais Hakochavim)


From: <baker@...> (Jonathan Baker)
Date: Tue, 4 Oct 94 10:54:09 -0400
Subject: Calendar Issues: Molad, Leap Months, Equinox

Mike Gerver asserted, (v15n33) on Feldman's authority, that the Amora
Hillel Sheni used a value for the length of the lunar (synodic) month
obtained by the Greek astronomer Hipparchus, of 29d 12h 44m 1h.

R' Ken Menken (v15n45) countered this with the quotation from the Talmud
that this value was known in Rabban Gamliel's grandfather's day, and so
it was known earlier than Hipparchus.

R' Abraham bar Hiyya, in his Sefer ha-Ibbur, (c. 1065 CE) which was the
source for a good part of Maimonides Hilchot Kiddush haChodesh, suggests
that Hipparchus may have been influenced in his calculations by the
Jewish knowledge of this value.

I'm afraid this doesn't hold much water.  Rabban Gamliel was active
around 20-40 CE (according to Steinsaltz' Reference Guide).  Even
allowing for longer than average lifespans and marriage ages, it is
unlikely that Rabban Gamliel's grandfather was active much before 50
BCE.  Sir Thomas Heath, in his "Aristarchus of Samos", places Hipparchus
around 125 BCE.

As for the origin of the 19-year cycle, that seems shrouded in mystery.
The Introduction to the Yale Judaica Series' translation and commentary
on Hilchot Kiddush haChodesh asserts that the lack of mention of the
19-year cycle in the Talmud is "unassailable" proof that it was unknown
by Jews in that time (Julian Obermann).  However, the Greek Meton is
alleged to have figured out this cycle around 437 BCE, and there is
cuneiform evidence that the Babylonians knew of this cycle even before
Alexander's occupation (before 332 BCE).  Since the Jews seem to have
been heavily influenced by the Babylonians in their astronomy, taking
the "chelek" unit (1/1080 hr, or 3-1/3 sec.)  from them, Neugebauer
contends that they got the 19-year cycle from the Babylonians.

Between Sinai and the Amoraic period, there is little to no indication
that the Jews used the 19-year cycle; rather, they presumably used the
subjective determinations laid out in Chapter 4 of Hilchot Kiddush
haChodesh.  Also see the perush of Ovadiah ben David on Hilchot Kiddush
haChodesh 1:2, which explains how when the difference between the lunar
and solar years reached a certain length, then the extra year would be

Who discovered it first, who discovered it independently, who
transmitted it to whom, this is difficult or impossible to determine.
How much weight one wants to give to a chain of tradition for which
there is little evidence, or to inference from non-Jewish historical
evidence, is entirely up to the individual.

On a related issue, David Curwin asks "When do we say the spring has
begun? ... we say "ten tal u'matar" on Dec. 4 ... it is not 60 days
after Sep. 22" (v15n39).  I worked out a possible answer to this a few
months ago, and would like some comment on its plausibility.

According to Feldman, the difference between the Jewish value for the
length of a year (attributed to R' Ada bar Ahavah) exceeds the actual
length of a solar year by 6m 20.35s, which adds up to about 1 day in 216
years.  Thus, the Jewish calendar gains, on average, 1 day in 216 years.
Assuming that the fixed calendar duplicates the timing of the
court-determined calendar, we have 3300 years since Sinai, which corres-
ponds to about 15 216-year periods.  One would expect to begin saying
"ten tal u'matar" then on Nov 20, which is 60 days after the autumnal
equinox, astronomically.  But we begin saying it on Dec. 4, which is 14
days later.  Perhaps those 14 days correspond to the 15-day excess (with
some possible error creeping in from the subjective intercalation not
exactly corresponding with the calculated intercalation) of the Jewish
calendar over the astronomical calendar.

	Jonathan Baker


From: Jeff Mandin <jeff@...>
Date: Wed, 5 Oct 94 18:04:53 -0400
Subject: Onaah and Interest-taking

Seth Weissman writes:

>So, compare these two scenarios:
>A) Miriam needs to borrow $100 to pay for her child's medical bills.
>Shimon offers to lend her the money for one week at a 100% rate of
>interest (In other words, she must pay him back $200 in one week).
>Shimon's Rabbi will tell them the transaction violates the prohibition
>of interest.
>B) Again, our Miriam needs $100 dollars.  This time, however, Shimon has
>learned from his mistake nad offers her $100 for her $200 wedding band.
>He says "I'll offer you $100 for that $200 ring."  The value exchanging
>hands is the same, but this time the Rabbi agrees that this transaction
>does not violate ona'ah because Miriam knows the value of what she is

I have doubts about your assertion that onaah and interest are treated
very differently in halacha.  Bava Metzia 61a actually asserts that one
prohibition could be inferred from the other, and the mishna in Bava 
Metzia Ch. 5 is very concerned w/ variations on the "Miriam" B) case, 
and prohibits a borrower from selling below market value to the one who 
lends him money, though I haven't seen discussion of a case where there
is no loan at all, such as in the case you describe.

You might want to take a look at the vort of R. Chaim Brisker (on BM 61a)
quoted at the beginning of the chapter on him in R. S. Y. Zevin's Ishim
v'Shitot.  R. Chaim views the overcharged amount to be "mammon shel
acherim" [money of others], and equivalent to stealing, rather than
merely profiting from someone's lack of knowledge.



From: "Ilene  M. Miller" <75107.146@...>
Date: 04 Oct 94 16:31:00 EDT
Subject: When do 19th birthdays coincide?

Several people have recently asked why their 19th Jewish and civil
birthdays sometimes coincide and are sometimes off by a day. The simple
and obvious answer is that sometimes 19 consecutive years will have the
same number of days in each calendar, and sometimes they don't.

But WHY are they occasionally off? Let's first look at the civil
calendar: Sometimes 19 consecutive civil years will include 4 leap
years, and sometimes they will contain five. Specifically, if the first
year is a leap year, then years 1,5,9,13,17 will be leap years. Or years
2,6,10,14,18 will be leap years.  Or years 3,7,11,15,19 will be leap
years. But if the fourth year of the group is a leap year, then years
4,8,12,16 will be leap years, giving a 19-year cycle which has one day
fewer than the others, which will increase the chance that the 19th
civil birthday will fall a day before the 19th Jewish birthday.

Now look at the structure of the Jewish calendar, and note that any
given 19-year stretch can easily have varying numbers of days. It is a
common fallacy to think that the Jewish calendar works strictly in
19-year cycles. The only aspect of it which follows a 19-year cycle is
which years have an extra month (Adar II). But the months of Cheshvan
and Kislev are both variable in length, sometimes having 29 days each,
sometimes 30 each, and sometimes Cheshvan has 29 and Kislev 30. These
lengths are determined mostly based on which day of the week Rosh
Hashana falls, but other factors are involved as well, so even if two
consecutive 19-year cycles began on the same day of the week, any given
19 year cycle can be quite different from the next.

This chart shows how many days were in each of the listed years. Keep in
mind that, for example, where it shows the year 1976 to have 366 days,
that also applies to any 12-month period containing February 1976 (such
as the year from 5/1/75 to 4/30/76). In the Jewish calendar, Cheshvan,
Kislev, and Adar are the variable months, so where the chart shows 5748
to have 354 days, that also applies to any year containing those months
(such as the year from Iyar 5747 through Nisan 5748, or from Cheshvan
5748 through Tishrei 5749).

1973...365       5733...383
1974...365       5734...355
1975...365       5735...354
1976...366       5736...385
1977...365       5737...353
1978...365       5738...384
1979...365       5739...355
1980...366       5740...355
1981...365       5741...383
1982...365       5742...354
1983...365       5743...355
1984...366       5744...385
1985...365       5745...354
1986...365       5746...383
1987...365       5747...355
1988...366       5748...354
1989...365       5749...383
1990...365       5750...355
1991...365       5751...354
1992...366       5752...385
1993...365       5753...353
1994...365       5754...355
1995...365       5755...384

This chart is based on the one above. It shows how many days are in a group of
19 consecutive years.

5733-51...6939      1973-91...6939
5734-52...6941      1974-92...6940
5735-53...6939      1975-93...6940
5736-54...6940      1976-94...6940
5737-55...6939      1977-95...6939

Note that the 19 years from 1973 to 1991 inclusive has the same number
of days (6939) as the 19 years from 5733 to 5751 inclusive. Rosh Hashana
5733 fell on Shabbos September 9 1972. Add 6939 days to that point, on
either calendar, and you will find that 19 years later, Rosh Hashana
5752 fell on Monday Sept 9 1991.

The following year, however, does not work out so nicely. The 19 years
from 1974-92 have 6940 days, but the 19 years from 5734-52 have
6941. That is why Rosh Hashana 5734 fell on 9/27/73. The next 19 Jewish
years contained one day more than the next 19 civil years, so Rosh
Hashana 5753 fell on 9/28/92, and the people born around Rosh Hashana
5734 will find that their nineteenth Jewish birthday is one day later
than their civil one. (See below for cutoff points.)

On the other hand, the 19 years from 1975-93 have 6940 days, while the
19 years from 5735-53 have 6939 days. And that will cause people born
then to have their nineteenth Jewish birthday to be a day BEFORE the
civil one. Rosh Hashana 5735 was on 9/17/74, but Rosh Hashana 5754 was
on 9/16/93.

The year after that, they match up again, for 1976-94 have 6940 days,
and 5736-54 also have 6940 days. Rosh Hashana 5736 was on 9/6/75, and
Rosh Hashana 5755 was on 9/6/94.

The current stretch of exact matches begins on Kislev 1 5735 (November
15 1974) and ends on Cheshvan 29 5736 (November 3 1975). People born
during that period will have their 19th birthdays match, going from
Kislev 1 5754 (11/15/93) to Cheshvan 29 5755 (11/15/94). It ends then
because Cheshvan had 30 days in 5736, but only 29 days in 5755.

That was a full year of matches. The prior stretch of matches, however,
was only nine months long, going from March 1 (1972 and 1991) to
November 6 (1973 and 1992), which corresponded to Adar 15 (5732 and
5751) to Cheshvan 29 (5733 and 5752). This is because February had 29
days in 1972 but only 28 in 1991. I have not looked at other years where
the dates coincide, but there are probably instances where the beginning
or end is affected by a long or short Kislev, or the presence/absence of
Adar Sheni as well.


End of Volume 15 Issue 60