Someone who stands in the courtyard of a catacomb is tahor as long as it is four cu-bits, according to Beis Shammai’s opinion. Beis Hillel say: Four handbreadths. [If] a beam was used as a cover for a grave, whether it is standing upright or lying on its side, nothing becomes tamei except what is opposite the opening [of the grave]. [If] one end [of the beam] was made into a golel for a grave, only four hand-breadths of the beam become tamei, provided that the rest is going to be chopped off. R’ Yehudah says: It is all regarded as one unit.

Someone who touches a tightly sealed barrel full of tahor liquid that was made into a cover for a grave becomes tamei for seven [days]. [However,] the barrel and the liquid remain tahor. Someone who touches an animal used as a cover for a grave becomes tamei for seven days. R’ Meir says: A living being does not transmit tumah as a cover.