וַיַּ֥עַשׂ אֶת־הַיָּ֖ם מוּצָ֑ק עֶ֣שֶׂר בָּ֠אַמָּה מִשְּׂפָת֨וֹ עַד־שְׂפָת֜וֹ עָגֹ֣ל ׀ סָבִ֗יב וְחָמֵ֤שׁ בָּֽאַמָּה֙ קוֹמָת֔וֹ וקוה [וְקָו֙] שְׁלֹשִׁ֣ים בָּֽאַמָּ֔ה יָסֹ֥ב אֹת֖וֹ סָבִֽיב׃
Und er machte das geschmolzene Meer von zehn Ellen von Krempe zu Krempe rund im Kompass, und seine Höhe betrug fünf Ellen; und eine Reihe von dreißig Ellen umfasste es ringsum.
Rashi on I Kings
Ten amohs from rim to rim. Through the middle, because the diameter of every round object is through the middle.
Rashi on I Kings
And a line of thirty amohs [the circumference]. This is what was mentioned, “All that have three handbreadth in its circumference have one handbreadth in its diameter.” Its circumference was thirty [amohs] and its diameter ten [amohs],37The diameter of 10 amohs is a rounded off number. A diameter of ten amohs results in a circumference of approximately 31.4 amohs. and he measures from its midst. In [Maseches] Eruvin.38See Maseches Eruvin 14a.
Rashi on I Kings
High. Its depth; and in Divrei Hayomim it states that he made it for the Kohanim to bathe and to immerse in.39See II Divrei Hayomim 4:6. Ralbag explains that in order to avoid the problem of מים שאובין [=drawn water] it was connected at its base to natural water that flowed into it from an underground source. The water from the underground wells flowed through the hollow feet of the oxen.