Four Domains on Shabbos
1. There are four different domains with regard to [the prohibition
against carrying between domains on] Shabbos (1): "Reshus HaYochid"
("private domain"), "Reshus HaRabim" ("public domain"), "Carmelis", and a
"Makom Patur" ("exempt area"). These concepts will be briefly explained
[in the following Halachos].
2. What is meant by a "Reshus HaYochid" ("private domain")? Any area of
at least four 'tefachim' (2) by four 'tefachim' (this is considered an area
significant enough to be of use), which is surrounded by "Mechitzos"
("partitions") that are at least ten 'tefachim' high (even if the
partitions are not complete).
[Therefore, the following areas are also defined as "Reshus HaYochid"]:
a) A trench ten 'tefachim' deep and four 'tefachim' wide (the sides of the
trench are considered halachic partitions).
b) A pit ten 'tefachim' deep, and four 'tefachim' by four 'tefachim' wide.
c) A mound ten 'tefachim' high, and four 'tefachim' by four 'tefachim' wide.
d) A movable object, for example, a cabinet, that is ten 'tefachim' high
[and four 'tefachim' by four 'tefachim,'], or a round barrel [ten
'tefachim' high], the circumference of which is large enough to enclose an
area four 'tefachim' by four 'tefachim.'
Even if these [areas or objects] listed above are located in the "Reshus
HaRabim" ('public domain') or in a 'Carmelis', they are considered separate
entities and judged as a "Reshus HaYochid" ("private domain").
The space above a "Reshus HaYochid," up to the sky, as well as the tops of
the partitions surrounding it, are governed by the same laws as the "Reshus
HaYochid" itself. Holes in the walls that open inwards towards the "Reshus
HaYochid," even if they continue through to the outside (with an opening to
the public domain), since one could potentially make use of the holes from
within the "Reshus HaYochid," they are considered part of the "Reshus
HaYochid" and share the same laws. (The laws regarding holes in the wall
that open towards the public domain alone are mentioned in the following law.)
(1) Carrying an object into or out of certain halachically defined domains
is one of the 39 Avos Melachos ("prototype prohibited activity"), and
therefore Biblically prohibited on Shabbos. This concept will be defined as
the chapter progresses.
(2) A 'tefach' ('handbreadth') is approximately 3 inches.