Mishnah Oholot 14:5: Two protrusions one on top of the other, and they have in them a handbreadth's space and between them a handbreadth's space, if there is impurity beneath them, what is beneath them is impure. Between them, what is between them is impure. On top of them, opposite it up to the firmament is impure. If the upper one extends over the lower one by a handbreadth's space, if the impurity is beneath them or between them, what is beneath them and between them is impure. On top of them, opposite it up to the firmament is impure. If the upper one extends over the lower one by less than a handbreadth, if there is impurity underneath them, what is underneath them and between them is impure. If it was between them or underneath the extended part, Rabbi Eliezer says beneath them and between them is impure but Rabbi Yehoshua says, between them and underneath the extended part is impure but underneath [both of] them is pure.

שְׁנֵי זִיזִין זֶה עַל גַּבֵּי זֶה וְיֵשׁ בָּהֶן פּוֹתֵחַ טֶפַח וּבֵינֵיהֶן פּוֹתֵחַ טֶפַח, טֻמְאָה תַחְתֵּיהֶן, תַּחְתֵּיהֶן טָמֵא. בֵּינֵיהֶם, בֵּינֵיהֶן טָמֵא. עַל גַּבֵּיהֶן, כְּנֶגְדּוֹ עַד לָרָקִיעַ טָמֵא. הָיָה הָעֶלְיוֹן עוֹדֵף עַל הַתַּחְתּוֹן פּוֹתֵחַ טֶפַח, טֻמְאָה תַחְתֵּיהֶן אוֹ בֵינֵיהֶן, תַּחְתֵּיהֶן וּבֵינֵיהֶן טָמֵא. עַל גַּבֵּיהֶן, כְּנֶגְדּוֹ עַד לָרָקִיעַ טָמֵא. הָיָה הָעֶלְיוֹן עוֹדֵף עַל הַתַּחְתּוֹן פָּחוֹת מִטֶּפַח, טֻמְאָה תַחְתֵּיהֶן, תַּחְתֵּיהֶן וּבֵינֵיהֶן טָמֵא. בֵּינֵיהֶן אוֹ תַחַת הַמּוֹתָר, רַבִּי אֱלִיעֶזֶר אוֹמֵר, תַּחְתֵּיהֶן וּבֵינֵיהֶן טָמֵא. רַבִּי יְהוֹשֻׁעַ אוֹמֵר, בֵּינֵיהֶן וְתַחַת הַמּוֹתָר, טָמֵא, וְתַחְתֵּיהֶן, טָהוֹר:

Mishnah Oholot 14:6: If they had in them a handbreadth's space but between them was less than a handbreadth's space, if there was impurity beneath them, what is beneath them is impure. Between them or on top of them, opposite it up to the firmament is impure.

יֵשׁ בָּהֶן פּוֹתֵחַ טֶפַח וְאֵין בֵּינֵיהֶן פּוֹתֵחַ טֶפַח, טֻמְאָה תַחְתֵּיהֶן, תַּחְתֵּיהֶן טָמֵא. בֵּינֵיהֶן אוֹ עַל גַּבֵּיהֶן, כְּנֶגְדּוֹ עַד הָרָקִיעַ טָמֵא: