[The following items also spread tumah and act as barriers against tumah:] ledges, balconies, dovecotes, overhanging boulders and rocks, windows for light, sharp rocks, and branch-canopies and protrusions that can support light plasterwork; these are the words of R’ Meir. The Sages say: medium plasterwork. What are branch-canopies? A tree that overhangs the ground. And [what are] protrusions? [Hedges] that extend out from a fence.

These [items] spread [tumah] but do not act as barriers [against tumah]: a chest, a box, a cabinet, a large straw basket, a large reed basket, and the water tank of an Al-exandrian ship — if they do not have [flat] bottoms or if they do not contain forty se’ah of liquid, which is two kors of dry measure; a curtain, a work apron, a bed cov-er, a sheet, matting, and a mat, if they have not been made into tents; the carcass of a domesticated or wild animal, and food that can become tamei. In addition to these, a mill powered by a person [spreads tumah but does not block tumah].

There are [items] that act as barriers [against tumah] but do not convey [tumah]: a loom that is ready for weaving, the ropes of a bed, garbage baskets, and window bars.

These items neither convey [tumah] nor act as barriers [against tumah]: seeds and plants that are connected to the ground, other than the plants listed above; hail-stones, snow, frost, ice, salt; [an animal] that jumps from one spot to another, [a person] who jumps from one spot to another, a bird that flies, a garment that flut-ters, and a ship that sails on water. [But if] the ship was tied with something that can hold it in place [or] a stone was placed on the garment, it conveys tumah. R’ Yose says: A house on a ship does not convey tumah.