Storage jars form one of the main ceramic vessels that were produced and abundantly used ever since pottery was invented. The need to collect, store, and distribute agricultural products such as grains, oils and wine in large vessels has littered excavation sites in Israel with a wealth of ceramic jar fragments of various designs, sizes and shapes.
Taking a closer look at the findings, three Israeli archaeologists, Hebrew University’s Ortal Harush, Israel Antiquities Authority’s Avshalom Karasik and Weizmann Institute’s Uzy Smilansky, found an astonishing common denominator among storage jars in Israel over a period of 350 years – the inner-rim diameter of the jar’s neck was almost identical.
The distribution of this diameter is consistent with measurements of the palm of a male hand and, according to the three, this match is not coincidental. It appears to reflect the use of the original metrics for the biblical measurement of the “tefach,” a unit of measurement that was used primarily by ancient Israelites and appears frequently in the Bible and is the basis for many Jewish laws.
“It was natural for the ancient potters to adopt the handbreadth-tefach-standard. It was a unit of length that was widely used in ancient times, and is mentioned both in Assyrian and Egyptian sources and in the Bible,” the researchers shared.
The team did 3-D scans of 307 Iron-Age jars found in Khirbet Qeiyafa from the time of the Judaean Kingdom in the early 10 century BCE, “hippo” jars found in northern Israel from the time of the Israelite Kingdom, the 9 Century BCE, and royal Judah Kingdom storage jars from the 8-7 Century BCE.
The researchers observed large variations between the jars-even those from the same time period and geographic region. Only one measure remained constant – the averaged inner-rim diameter which always measured, with a standard deviation, between 8.85 and 8.97 centimeters.
The distribution of this diameter is statistically identical to the hand’s breadth of modern man, as described in Jewish law. To gain data on the standard measure of a modern man’s palm, the team tapped measurements taken by the US Army when ordering gloves for their soldiers, which is consistent with the measurements taken from the ancient jars.
Though human heights and weights have changed over time due to improved diet and health, previous research has shown that palm dimensions have not changed much over the last 3,000 years.
As to why the inner rim remained consistent while the overall shape of the jar varied so much, the Israeli researchers offered several theories.
It was a natural choice for ancient potters to use their palms as the standard diameter for jar openings-it was easy to implement when working on the wheel: the potter could simply use her or his palm as a tool.
Further, storage jars were multiuse items, which meant their openings had to be large enough to allow for cleaning between uses and this involves fitting your hand into the jar.
However, there is another ancient aspect that may explain the connection between uniform neck diameters. It is based on the highly regarded and observed purity laws in the Torah. The Book of Shmot (Numbers) deals with the question: What is the status of jars that were left in the vicinity of a corpse-are they impure?
“This is the law, if a man dies in a tent, anyone entering the tent and anything in the tent shall be impure for seven days. Any open vessel which has no seal fastened around it becomes impure.” (Numbers 19: 14-15)
It is clear from this passage that the contents of a jar become impure-and therefore unusable- unless there is a special seal on its top. This ruling had serious economic ramifications. Imagine having to throw out valuable stores of grain and oil after a death in the family tent.
Subsequent Jewish traditions quantified these rules of impurity, stating that the minimum opening size through which impurity may enter is the square of a hand’s breadth by hand’s breadth.
“According to the Oral Tradition, it was taught that the verse is speaking only about a ceramic container, for it is a container that contracts impurity only through its opening.” (21.1) – Maimonides’s Code of Jewish Religious Law, Mishneh Torah.
Maimonides brings down an ancient tradition vis a vis the laws of impurity, stating that a round opening with a maximum diameter of one hand’s breadth, or tefach, would ensure that the jar’s content would still be pure even if it were stored near a corpse. Therefore, it would make sense that potters would create storage jars with a tefach opening.
Over time, rabbis attempted to provide conversions of the traditional biblical measurements to our modern measurement. The conversions for the tefach vary, with competing approaches brought forth by Rabbi Avraham Chaim Naeh and the Chazon Ish, both 20th-century Orthodox rabbis who lived in Israel.
According to Rabbi Naeh, one tefach equals 8 cm, and according to the Chazon Ish one tefach equals 9.6 cm. The uniform opening of the ancient storage jars, which falls between 8.85-8.97 cm, falls squarely in between these two opinions and may shed light on the dimensions of the biblical tefach and elucidate on how tall your sukkah can be, down to the last centimeter.