Where would Joseph Smith have learned about the names, relative amounts and functions of ancient weights and measurements?

In the middle of Alma 11 in the Book of Mormon, a detailed description of measurements is outlined. What is impressive is that the measurements correspond with what we know of other ancient cultures:

Fractions were a part of weights and volume measures actually used in the ancient Near East
No ability to express a fraction with a numerator greater than one in the Near East
Use of weights and measures rather than coins as in other ancient cultures

In terms of the names used, John Welch notes:

The term shilum closely approximates the Hebrew ¡illum (or shillum) which means “repayment,” “recompense,” or “retribution” (see Hosea 9:7; Isaiah 34:8; Micah 7:3). Moreover, both the Nephite and Hebrew expressions may link to the Akkadian ¡illum (or shilum) in Mesopotamia, which refers to an “area measure.”
For the name senum, the correspondences come from Hebrew and Egyptian. On the Hebrew side, “senum” appears to derive from a root having two consonants, sn, perhaps coupled to the Akkadian nominative singular termination -um.24 An obvious candidate is seni or senayim (dual form), from the Hebrew root for “second,” “two,” or “double.” It is not unreasonable linguistically to see the Hebrew for two as a close relative of the Nephite senum, particularly in view of dialectical exchanges in early Hebrew between s and ¡ (e.g., Judges 12:5–6). The same phonological equivalent may also be seen in the ancient Egyptian cognates for two: sn, snw, snwy, and sny, and Coptic snau.
– John W. Welch – Weighing and Measuring in the Worlds of the Book of Mormon

Why would Joseph Smith take a chance on creating a measurement system that could be proved to be anachronistic?

See:

John W. Welch – Weighing and Measuring in the Worlds of the Book of Mormon

Add