פירוש על בבא בתרא 3:8

אין עושין חלל תחת רשות הרבים – even if he accepted upon himself every blast/wind that comes from the consequences of this, for people do not want to cause damage and to go to court to judge on the matters of their money.

Introduction Mishnah eight deals with permitted and not permitted damages that an individual might create to the public domain.

רבי אליעזר מתיר – as long as they cover it with force in order that a wagon carrying stones will travel upon it, and we should not worry lest sometimes the covering will be ruined. But the Halakha is not according to Rabbi Eliezer.

One may not hollow out a space underneath the public domain [such as] cisterns, trenches or caves. Rabbi Eliezer permits it if it is such that a wagon loaded with stones can [safely] go over it. One may not dig out a space underneath the public domain lest the ground crash in. According to Rabbi Eliezer if the ground is strong enough one may do so.

זיזין – small floor beams.

Projections and balconies may not be built into the public domain; but if a man wishes to build a [projection or balcony] he may withdraw [his wall] within his own domain and build out from it. If he bought a courtyard in which were already projections and balconies, his right to maintain them may not be disputed. One may not build projections of any nature into the public domain, but one may pull back his property and build a projection out from there. If he bought property that had such projections we assume that they were not built on public property and we do not make him remove the projections.

גזוזטראות – large beams lest the members of the public domain stumble against them.

Questions for Further Thought:
• Why might one have thought that it is forbidden to build a projection or a balcony even within one’s own property?

כונס לתוך שלו – brings into his land like the measure of the removal of the small floor beams and take them out.

הרי זו בחזקתה – we load them for the purchaser and we state that the person who sold it to him and brought them into his own [home].