We wrote "the field is metamei in every direction from the grave for the length of an average furrow, or fifty amos, resulting in the area of one hundred amos by one hundered amos surrounding the grave (Rash Ahalos 17:1)".

This is what is stated in the Mishnah Ahalos 17:1, cited in the Gemara here, that if one plows up a grave, this makes a Beis HaPras of a full Ma'aneh of 100 amah. This means that we can consider the grave as being in the center of a square of 100 amah by 100 amah, as the Mishnah Ahalos there states that the size of the Beis HaPras is 4 sa'ah. The Rash there writes that Beis Sa'ataim [2 Sa'ah] is 100 amah by 50 amah, as stated in Eruvin 23b. It follows that 4 sa'ah is 100 amah by 100 amah. Since the grave is in the center of a square; namely the Beis HaPras; of 100 amah by 100 amah, this means that the distance from the grave to the edge of the square on each side is 50 amah. This is why we wrote 50 amah in every direction. When Rashi wrote 100 amah in telem echad he was referring to the total length of the square on each side.

I found, bs'd, a source for what we wrote in the Shitah Mekubetzes Berachos 19b DH Tirgama. The Gemara there refers to Beis HaPras and Shittah Mekubetzes explains it. He writes:

" This is a field where a grave was plowed. The Chachomim said that for every 50 amos one must be concerned that there may be a bone the size of a barley corn that the plough dragged along".

Shittah Mekubetzes writes that the bone might have been moved 50 amos by the plow.

I found that "Ginzei Rishonim" (published by Rav Moshe Hirschler) on Berachos 19b, page 322, cites the above passage in Shittah Mekubetzes in the name of Rabeinu Avraham Alshabili [the father of the Ritva. Incidentally I have sometimes noticed that passages in Shittah Mekubtezes are to be found word by word in the Ritva, and now I see that Rav Hirschler ascribes it to the Ritva's father - DB].

In the notes at the bottom of Ginzei Rishonim, #89, he asks on Rabeinu Avraham and the Shittah Mekubetzes that in Moed Katan 5b, Ahalos 17:1 and other places, we see that Beis HaPras is 100 by 100 amah from the place of the grave, so where did the Shittah get 50 from?!

However, I think that according to what I wrote above we can explain the Shittah. The plow is capable of dragging for up to 50 amah a human bone; which after the dragging is still big enough to be the size of a barley corn. This means that a square which is 100x100 amah around the grave, is still in doubt as possibly containing the remains of a bone.

[Don't ask me why it is a square not a circle].

This appears in Chidushei HaRitva:-

I will just point out that the explanation that I cited above in the name of Shittah Mekubetzes and the father of the Ritva on Berachos 19b, also seems to be stated verbatim in Chidushei Ritva Berachos 19b; published by Mosad HaRav Kook; also edited by Rav Moshe Hirschler. Again, the idea is that the plow is capable of moving a human bone "Etzem kiSe'orah"; the bone the size of a barley corn; up to 50 amah in every direction, and therefore a Beis HaPras is a square 100 amah by 100 amah since this is the area in every direction that the bone might have been moved to.

Dovid Bloom

For the moment I just want to relate, bs'd, to the first point; is plowing ever done Shesi v'Erev? I will try and cite a few sources.

1) See Gemara Bava Basra, top 103b, where the Gemara discusses someone who sold a field, part of which is difficult to plow. One of the examples (top line 103b) is "Keshurah". Rahsbam DH Keshurah writes that because of the difficult terrain, all plowing must be done Shesi v'Erev. We learn that some land requires plowing Shesi v'Erev.

2) See Yevamos 63a where Rabbi Elazar said that there is no occupation lowlier than working on the land. The Gemara relates that R. Elazar once saw land that was plowed breadthways. He commented that even if the land will now be plowed also lengthways it would still be more profitable to go into business, rather than agriculture. We learn from the Gemara that R. Elazar admits that if one plowed lenghtways after plowing breadthways this is good for the crops, but R. Elazar was in general not enthusiastic about farming and preferred trading.

3) We can also say that this is especially true in Eretz Yisrael, since the Gemara Shabbos, top 73b, states that in Eretz Yisrael one must first sow the seeds and then plow. Rashi DH BE'Y writes that the land of Eretz Yisrael is hard [I want to say that this is because Dvorim 8:9 says "the land whose stones are iron" - DB] and one cannot cover over seeds without plowing first. It can be suggested that in Eretz Yisrael it is necessary to plow both Shesi and Erev in order to soften up the land.

4) I got the above ideas from Maseches Kutim, published by Machon HaTalmud HaYiraeli, page 144 DH veOd, in a commentary written by the author of "Chok Moshe"; Rav Moshe Yehudah Leib Berman HY'D.

5) I will try, bs'd, in further replies, to relate more specifically to the Sugya of Beis HaPras.

Good Shabbos

Dovid Bloom

Follow-up reply:-

1) Just one more source about Shesi v'Erev plowing. This is from Bava Metzia top 107a [it is cited by Toras Chaim on Bava Basra 103b mentioned above in no. 1)]. The understanding of the Gemara is according to Tosfos there DH Hai Man, that the Gemara tells us that if someone wishes that his field should be strong and fruitful he should plow it one year Shesi and the next year Erev. We learn from this that it is healthy and productive for the field to plow it in different directions in different years. So even if we say that for a regular field one does not usually plow both shesi and erev in the same year, nevertheless in different years it is recommended to do so and this way the bones may have been dispersed throughout the entire field.

2) I found, bs'd, in "Mishnah Achronah" on Ahalos 17:1, that the Beis Arba'ah Sain of the Mishnah there means both length and breadth of up to 100 amah, but is not referring to plowing lengthwise and breadthwise at one time. However the reason that Mishnah Achronah writes this is because if the plowing would be like that in one go, this would mean he would have to "turn over" the plow. If he turns over the plow, the Mishnah states later on that there is no Din of Beis HaPras. I think that the Mishnah Achronah is referring to Mishnah 17:2 which states "Oh She-Nier Hamachreishah"; or he shook the plow. If he shook the plow, this shakes out all the earth from the plow so if there is a barley-sized bone, it cannot be taken any further. It follows that if he plows both lengthwise and breadthwise in one go, this means that when he changes direction any bone would fall out together with the earth and cannot spread any more. Mishnah Achronah writes that instead one has to say that he started from the place of the grave and plowed lengthwise and then went back and started again from the grave and plowed breadthwise.

KOL TUV

Dovid Bloom

The difference between a field where a kever was plowed and a field where a kever was lost:-

1) Concerning a scenario where there was known to be a kever aveid, see the Rash on 18:3 who writes that what is stated throughout Shas that Beis HaPras is only derabanan, only applies to a field that was plowed, but if the grave is lost in the field, this is forbidden mideoraisa if it is in Reshus Hayochid (see Mishna Taharos 6:6 that one is stringent on a doubt in tumah in Reshus Hayochid).

2) The Mishnah Ahalos 18:5 tells us how to be metaher a Beis HaPras. The Bartenura writes that this only applies to a field where the kever was plowed up. Tosfos Rabbi Akiva Eiger writes that the technigue mentioned in the Mishnah would not help if a grave had been lost, because if this had happened the question is whether the grave is tamei as Ohel, not merely for Maga and Masa. Tiferes Yisroel 18:46 writes that one would have to dig down till one reaches the rock and remove all the earth, as in Mishnah Ahalos 16:4. It seems that a check of Sheis v'Erev is not sufficient if there was known to be kever aveid. Tosfos DH Menapeach; who writes that Bais HaPras is only a chumra deRabanan; would not apply to a kever aveid, which according to the Rash is tuma deoraisa.

Dovid Bloom

The Mishnah Achronah is discussing a field where a grave was plowed up. 100 by 100 in a Sadeh She-Nechrash Bah Kever is indeed only a Gezera but a field where a grave was lost is deoraisa; as the Tosfos Yom Tov 18:3 DH Sadeh writes in the name of the Rash; that it is logical that a Sadeh She-Avad in Reshus Hayochid is deoraisa.

Yasher Koach

Dovid Bloom