Ohalot, Chapter Fourteen, Mishnah Six
This mishnah is a continuation of yesterday’s mishnah, concerning two projections, one above the other.
1) If they had a width of a handbreadth but there was not a space of a handbreadth between them:
a) If there is uncleanness beneath them, what is beneath becomes unclean;
b) If it is between them or above them, everything directly [above] to the sky becomes unclean.
Since there is not a handbreadth in between the two projections, there is not an ohel in this area. However, there is still an ohel below the bottom projection.
If the uncleanness is found beneath both projections, then it is confined to this area. The lower projection forms an ohel and prevents the impurity from spreading above.
However, if the uncleanness is between them, it does not spread throughout an ohel. It only defiles that which is directly above it, just as it does if it is found above the top projection. The upper projection does not prevent the impurity from going above because it is not an ohel, but the bottom projection does prevent the impurity from going below.