In a location which is considered public domain or a carmelis, it
is forbidden—halachah l’Moshe Misinai- to carry an object more than
four amos on Shabbos if there is no eruv.
The amah should be measured according to the smaller of the generally
accepted opinions of the size of an amah: 48 cm.
It is permitted lechatchilah to carry an object less than four amos
provided that it is moved only once. To carry on object several times in
succession, each time less than four amos, is forbidden, even if the person
who carries it stops to rest each time (resting, like putting the object down,
breaks the continuity of the action) or places the object on the ground each
time. Carrying an object less than four amos several times in succession is
one of the eighteen things that were forbidden by the rabbis “bo b’yom”
(see Shabbos 17b) to prevent a person from carrying an object four amos
without realizing it. If a person stops before moving four amos to adjust his
burden—not to rest—it’s as though he didn’t stop at all and violates the Torah
prohibition of carrying four amos in the public domain. A person who stops
just to avoid violating the Torah prohibition is also not considered to have
stopped to rest. He must actually sit down each time in order to avoid
violating the Torah.
The rabbinical prohibition of carrying an object over a distance that is
greater than four amos by resting or putting it down before traversing four
amos applies only when a person has the intention of moving the object more
than four amos. But if he intended to carry it less than four amos, put it
down, and then changed his mind and decided he wanted to move it a little
further (less than four amos), he is allowed to do so.
The prohibition of carrying more than four amos through a succession of
moves that are less than four amos applies even ben hashemashos. We do
not apply the principle that in cases of doubt, rabbinical prohibitions are
suspended. The reason is that if sequential carrying of less than four amos
were allowed, it would lead to frequent violations the Torah. The prohibition
of sequential carrying applies even in a carmelis. Does it apply to a
carmelis ben hashemoshos? That is disputed, but in practice we are
lenient if the object is transported for the sake of a mitzvah or because it
is urgently needed.
The prohibition of carrying less than four amos applies only to
individuals. According to some, this allows for moving objects by relay, i.e.,
one person transferring the object to another. In this way, an object could be
transported great distances without violating the prohibition of carrying. Is
it permitted for two people to do this, one handing the object to the other
and then moving forward to receive it? The פר"מ implies that it would be
permitted in a carmelis, but in the public domain it should be avoided.
Others hold that moving objects by relay more than four amos is forbidden. In
practice, carrying by relay is allowed, but it is desirable to be stringent
and avoid carrying in this way unless it is necessary for the sake of a
mitzvah. When carrying by relay, the people involved do not have to rest or
sit down because the carrying done by one person is not considered an
extension of the carrying done by the other.
In the public domain and in a carmelis, the prohibition of carrying
pertains to the distance an object is moved ie., it may not be carried more
than four amos, but to carry an object from the public domain to the private
domain or even to a carmelis is strictly forbidden, whatever the
distance may be.
A pillar, a bench, or a wall in the street that is ten tephachim
high and four tephachim wide, and a pit that is ten tephachim deep and
four tephachim wide are considered to be set apart from the public domain.
Their surfaces are considered private domain, so it is forbidden to take an
object in the public domain and to place it upon (or into) them. (A wall that
surrounds the public domain is considered private domain even if it is not
four tephachim wide.) Even when a pillar, bench or wall is not ten tephachim
high, if it is set into the ground, its surface is considered to be a separate
domain, a carmelis, and it is forbidden to transfer an object to them
from the public domain. For this reason, it is forbidden to toss things
into a garbage can from the public domain, or to lift a child from the public
domain and seat him on a fence or even on a bench. Many people are not aware
of this.
A human being exists within a physical domain. He does not constitute a
physical domain. Therefore, even though a person who stands in the public
domain is more than ten tephachim tall and four tephachim wide, he is not
considered a separate domain.