[Avodah] What's a city?

[Micha Berger]

On Tue, Jun 19, 2012 at 02:38:35PM -0400, David Riceman wrote:
> In OH 398 it says that a house within 70 and 2/3 amos of a city is part  
> of a city.  But I can't find a definition of a city.

For the purposes of techum Shabbos:

A city has to have a minimum of 6 homes within 70-2/3 amos of each other.

The borders are then drawn as east-west and north-south lines that run
70-2/3 amos beyond the last house of the grouping in each of the four
compass points.

The shiur of 70-2/3 amos might be inexact lechumerah. The real derivation
is the side of a square of an area of 5000 sq-amos, the area of the
chatzeir hamishken. (Eruvin 23b) This would give it a real value of
70.7107... amos. My "might" is because I don't know if we require the
chumerah lemaaseh, or if it's just a shorthand for discussion purposes.

BTW, you effectively get 2004 amos beyond the city border, since the
next 4 amos beyond the actual techum are mutar as well.


If you don't live in a city (as defined above), you can still get to
a neighbor's house if his house's techum overlaps yours. So you can
get there even if they are over 1-1/8 mi (or 1.8km) apart. Or 9 houses
away or so in your hypothetical 10 acre per home community. (I got that
number using square lots. I'm also assuming an 18" ammah, which I would
think is fine for the derabbanan limitation of only 2000 ammos.) You
just can't make one big techum around both.

But that's not how Jews lived in Chazal's day. They were agrarian,
but all the fields surrounded a denser living area. This is not only an
issue with the cities given the levi'im, but even impacts how many of
us daven maariv -- Barukh H' LeOlam was invented around the fact that
everyone had to return from the area around the city in the dark.

Tir'u baTov!
-Micha

-- 
Micha Berger             Spirituality is like a bird: if you tighten
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