1)

(a)In discussing whether something that is Ma'ahil over a Meis transmits Tum'ah on to Keilim on the one hand, and protects from Tum'ah on the other, the Mishnah teaches us that there are some things that can achieve both - some that can bring Tum'ah but not protect from Tum'ah, some that can protect from Tum'ah and not bring Tum'ah, and some that can do neither.

(b)The Tana lists Shidah, Teivah u'Migdol (a large crate [see Tos. Yom-Tov], a box or a drawer and a cupboard) - under the first category (those that both transmit Tum'ah on Keilim and protect from Tum'ah).

(c)The list continues with Kaveres ha'Kash - which is a large bee-hive like box made of stubble, or of willow or palm branches, and 'Kaveres ha'Kanim' - a similar shaped sort of basket made of reeds (see Tiferes Yisrael).

(d)And it adds the pit of an Alexandrian ship - which is used to store water for long journeys.

2)

(a)All of the above must have a flat base (see Tiferes Yisrael) - and must be large enough to hold at least ...

1. ... forty Sa'ah in liquid measure.

2. ... two Kur (which is the equivalent of sixty Sa'ah) in solid measure.

(b)Otherwise, they will not save Keilim from Tum'ah - since they are themselves subject to Tum'ah (see Tos. Yom-Tov).

3)

(a)The Tana includes in the current list, a curtain, a tanner's apron, a leather mattress, a linen sheet, a Mapatz and a Mechtzeles, under certain conditions. A ...

1. ... Mapatz is - a reed mat.

2. ... Mechtzeles is - a mat woven out of canes.

(b)The Mishnah includes them - provided they that have been placed there specifically to serve as an Ohel ...

(c)... since it is only an Ohel that protects what is above or below it from Tum'ah, even though it is itself subject to Tum'ah.

4)

(a)The Tana also includes in the list, a herd of Kasher or of non-Kasher animals and Mechonos Chayah ve'Of.

(b)Besides the fact that they are still, the Tana also requires the animals - to be standing (with no gaps in between them (the head of one between the legs of the one in front of it), in order to protect Keilim that are on the other side of the Meis.

(c)Mechonos ha'Of - are animal and bird cages (see Tos. Yom-Tov).

5)

(a)The Tana includes a bird in the list - provided it has alighted (from its flight) on a wall or a tree to which it is tied (see also Tos. Yom-Tov & Tiferes Yisrael).

(b)He also inserts ha'Oseh Makom Leveinah be'Shibalim, meaning that - one makes oneself a house-like cavity among the stalks of corn (see also Tos. Yom-Tov).

(c)And he adds Eirus, Kisum, Yarkos Chamorim and Dala'as Yevanis (four kinds of vegetables) - which all possess large leaves (see also Tos. Yom-Tov).

6)

(a)This Mishnah concludes with - food that is Tahor (see Tos. Yom-Tov).

(b)According to R. Yochanan ben Nuri, the only food that protects from Tum'ah is - a round cake of figs (which tends to be extremely large) ...

(c)... because it is the only food beneath whose shade people would sit (it was used as an Ohel).

(d)The Halachah - is like the Tana Kama.

7)

(a)Continuing with the previous list of objects that serve as an Ohel to transmit Tum'ah on to Keilim on the one hand, and to protect from Tum'ah on the other, the Tana begins with Zizin and Gizriyos, both kinds of external window-ledges - made of a single piece of wood or stone and structures made of the same material, respectively.

(b)He continues with dove-cots (see Tos. Yom-Tov), kinds of rocks and Geharim (or Gecharim [see Tos. Yom-Tov]) - holes that allow sunlight to enter the room.

(c)And the list continues with Shenanim - tops of rocks (see Tiferes Yisrael).

8)

(a)The list concludes with Sechachos and Pera'os, which, according to R. Meir, must be able to support soft Ma'azivah (cement), which comprises - a ceiling made of willow branches or canes, with a little cement that one pours on it.

(b)The Chachamim maintain that - it must be able to hold regular Ma'azivah.

(c)The Halachah is - like the Chachamim.

(d)Sechachos are the branches of a tree that are hanging over a Meis, Pera'os - thorns and thistles that one places atop a wall that are protruding into the street.

9)

(a)The Mishnah now lists those things that transmit Tum'ah (ne'Ohel) on the one hand, but do not protect from Tum'ah on the other, starting with - Shidah, Teivah u'Migdal, Kaveres ha'Kash, Keveres ha'Kanim and Bor Sefinah Alexandris that do not have a flat base ...

(b)... or that do not hold forty Sa'ah of liquids (two Kur of solids) ...

(c)And the Tana adds to the list ...

1. ... a curtain, a tanner's apron, a leather mattress, a linen sheet, a Mapatz and a Mechtzeles - that were not placed there specifically to serve as an Ohel (if, in their capacity as a cover, they happen to overlap a skylight as well) ...

2. ... the carcass of an animal and Tamei food (see Tos. Yom-Tov) ...

(d)... and a hand-mill (see Tos. Yom-Tov DH 'Mosaf Aleihem' & 'ha'Rechayim shel Adam') - but not one that is attached to a pole that is rotated by an animal, which is not subject to Tum'ah, since it cannot be moved from its place.

10)

(a)The Mishnah now presents a new list beginning with the warp that is stretched on the loom. The category now under discussion is - the one that is Chotzetz before Tum'ah but is not Meivi Tum'ah (see Tos. Yom-Tov).

(b)When the Tana says Not Meivi Tum'ah, he means that - (as opposed to the first category) if the Tum'ah is on one side of the object, it does not transmit Tum'ah to Keilim on the other side.

11)

(a)The Tana adds Chavilei ha'Mitah, ha'Mashpalos and ha'Serigos she'ba'Chalonos. Chavilei ha'Mitah are - the ropes that are attached to a bed in criss-cross fashion (see Tiferes Yisrael).

(b)Mashpalos are large cartons that are used to remove manure and Serigos she'ba'Chalonos - windows made of latticework.

(c)All of the above will also transmit Tum'ah from one side to the other - if there is even one gap of a square Tefach (see also Tiferes Yisrael).

12)

(a)The final list begins with seeds and vegetables that are still attached to the ground - incorporating things that neither transmit Tum'ah nor do they protect from Tum'ah ...

(b)... because every item in this list has no permanence (Tiferes Yisrael).

(c)When the Tana says (with reference to vegetables) Chutz min ha'Yerakos she'Manu, he is referring to - the long-lasting vegetables that are listed in the first Mishnah.

(d)And he continues with Kipas ha'Barad, which (besides a piece of hail), might mean - an arched-shaped piece of hail.

13)

(a)Next on the Tana's list are Sheleg, K'for - flowing water that has frozen, G'lid - a river that has frozen over, and Melach.

(b)All of these do not serve as a Mechitzah - because they are destined to melt and flow away or disintegrate.

(c)ve'ha'Doleg mi'Makom le'Makom ve'ha'Kofetz mi'Makom le'Makom might refer to an animal and a person respectively. Alternatively - they refer to a person (see Tos. Yom-Tov) who is skipping or jumping, respectively.

(d)The third item in this group is - a bird in flight (see Tos. Yom-Tov).

14)

(a)The Tana includes in the current list ...

1. ... a Tallis - that is flapping in the wind.

2. ... a boat - that is floating on the water.

(b)On the other hand, he includes in the group of those that bring Tum'ah ...

1. ... the same Tallis - if a stone has been placed on the end to stop it from flapping.

2. ... a boat - if it has been tied in a way that it is no longer able to float.

15)

(a)R. Yossi rules that - a boat-house does not bring Tum'ah (see Tiferes Yisrael).

(b)Assuming that the boat-house is able to withstand a regular wind [see Tos. Yom-Tov]) - he is speaking where it is raised and there is a Meis underneath it (see Tos. Yom-Tov).

(c)The Halachah is - like the Tana Kama (who declares any Keilim in the boathouse, Tamei).

16)

(a)The Mishnah now cites a case where there are two earthenware barrels, each containing half a k'Zayis of Meis, in a room - in which case, any Keilim in the room are Tamei.

(b)The barrels however, will remain Tahor - provided the lids on both barrels are sealed ...

(c)... because whereas a sealed lid prevents whatever is inside a K'li Cheres from becoming Tamei, it does not prevent Tum'ah that is inside it from escaping.

(d)If one of the barrels is subsequently opened - then it too, becomes Tamei, but not the one that is still sealed.

17)

(a)The Mishnah equates the basic Halachah in the previous case to one where two Chadarim open into the Bayis. The case is - where the two rooms, each containing half a k'Zayis of Meis, open into the Bayis (which opens into the street), and their doors are all shut.

(b)The Tana rules there that - the Bayis is Tamei, but the rooms remain Tahor ...

(c)... because the two half-k'Zeisim are destined to be removed through the Bayis, but not through the rooms.