Rabbi Nehemiah was a rabbi who lived circa 150 AD (fourth generation of tannaim).
He was one of the great students of Rabbi Akiva, and one of the rabbis who received semicha from R' Judah ben Baba
The Talmud equated R' Nechemiah with Rabbi Nehorai: "His name was not Rabbi Nehorai, but Rabbi Meir."[1]
The Mishnat ha-Middot argues against the common belief that the Bible defines the geometric ratio (pi) as being exactly equal to 3, based on the description in 1 Kings 7:23 (and 2 Chronicles 4:2) of the great bowl situated outside the Temple of Jerusalem as having a diameter of 10 cubits and a circumference of 30 cubits. He maintained that the diameter of the bowl was measured from the outside brim, while the circumference was measured along the inner brim, which with a brim that is one handbreadth wide (as described in the subsequent verses 1 Kings 7:24 and 2 Chronicles 4:3) yields a ratio from the circular rim closer to the actual value of .[1]