OPINIONS: The Mishnah states that the Kuchin (graves) which a person must supply when he agrees to supply a burial cave must be four Amos long, seven Tefachim high, and six Tefachim wide. They must be four Amos long because the average person is three Amos long, and another Amah is needed for the casket (see RASHBAM to 100b, DH veha'Kuchin). The width must be six Tefachim because a person of average size is six Tefachim wide when fully clad, and, without clothing, his body can fit into a casket which can fit into a grave which is six Tefachim wife (see TOSFOS to 101a, DH v'Rachban). Why must the height of the Kuchin be seven Tefachim?
(a) The RASHBAM (100b, DH v'Ruman) explains that the actual height of the casket is six Tefachim (to fit the Mes). Another Tefach is added so that the Tum'ah will be contained within the casket and not cause those who walk over the cave to become Tamei.
TOSFOS notes that the Rashbam's explanation does not mean that a person who walks over the grave does not become Tamei (see Tosefta 6:7) since the Tum'ah stays below the ground (it is not "Boka'as v'Olah"). The Gemara in Berachos (19b) notes that Kohanim are permitted to skip over graves in order to see a king (and recite the blessing upon seeing a king). This implies that although a grave (with a one-Tefach gap between the top of the casket and the roof of the grave) does not exude Tum'ah d'Oraisa, one who walks over such a grave normally would become Tamei mid'Rabanan. (The Rabanan did not enact such Tum'ah in the case of Kohanim running to see a king.) The RITVA explains the reason for this Gezeirah as follows. The Rabanan knew that not all graves were made in this manner, and thus one who walks over graves should be Tamei mid'Oraisa. They therefore decreed that Kohanim should never walk over any graves, lest they walk over a grave which would cause them to become Tamei. The Rabanan suspended their decree in the case of a special Mitzvah-need, such as seeing a king.
(b) Tosfos quotes the RIVAM who explains that leaving a Tefach of space between the casket and the roof of the grave helps prevent the Tum'ah from penetrating above the grave only when there is also an opening at the side of the casket (see MESORES HA'SHAS #7) which lets the Tum'ah into the grave. Without such an opening at the side, leaving a one-Tefach gap only causes more Tum'ah, not less. The Rivam explains that if there is no opening at the side of the casket, the entire casket is considered to have Tum'as Mes, and the Tum'ah rises above the ground, opposite the entire casket. If there is an opening at the side of the casket, the Tum'ah is considered to have a place to go, so to speak. In this way, the Tum'ah is contained inside the grave and does not rise through the top of the grave. (Y. MONTROSE)


OPINIONS: The Gemara quotes the Mishnah in Ohalos (16:3) which states that when one finds a buried corpse which was not buried in a cemetery, he is allowed to move the corpse and give it a proper burial somewhere else. However, he must also take the Tefusah, the additional three Tefachim of earth underneath the corpse. The RASHBAM (DH Mes) explains that the three Tefachim of earth underneath the Mes has the status of the Mes itself, and thus it also must be given a proper burial.
The Rashbam explains that the Mishnah's law is based on the assumption that when a corpse is found buried alone with no indication that the area was designated as a cemetery, one may assume that it is only a temporary grave (that is, the people who buried the corpse were rushed, or were unable to get to a proper cemetery). Accordingly, disinterring the corpse and transporting it to a permanent grave is permitted. The RAMBAN in TORAS HA'ADAM (Shar ha'Kevurah) includes this situation as one of three times when one is permitted to move a Mes. This is also the Halachah as recorded by the SHULCHAN ARUCH (YD 363:1).
The Gemara is not clear about the conditions of the case. Does the allowance to move a corpse apply even when a family buried a dead person in a cemetery but later claims that they had in mind to bury him there only temporarily? Would they be allowed to move the corpse?
(a) The SHO'EL U'MEISHIV (1:231) writes that a relative may not claim that he intended to bury his relative in the cemetery only temporarily. A relative is presumed to be "Noge'a b'Davar" (partial to the outcome of the case). A similar ruling was issued by the CHASAM SOFER (6:37). The MAHARAM SHIK (YD 354) adds that even if once could claim that he had in mind to make this burial only a temporary burial, he would have to declare before the burial that "this burial is only temporary." This is also the opinion of the TZITZ ELIEZER (10:40).
(b) The SEDEI CHEMED (Mareches Aveilus 135) argues that it is possible to believe a relative's claim in such a case. (Y. MONTROSE)