Eiruvin 58a, b

Today's daf focuses on how we should actually survey and measure the Shabbat boundaries.  In 58a, we are told about which ropes are to be used and why.  We also learn the reasons for the length of rope to be used.  A reference to masechet Sota refers to the type of rope used for that ritual.  That very short aside created some anxiety on my part knowing that I will be delving into that ritual in future learning (there are very disturbing, strangely-like-witchcraft rituals to come).  In 58b, we learn the specific ways that surveyors are to measure distance when they come upon hills, mountains, canyons, walls, or fences.  The notes offered in the Koren translation were extremely helpful to me in today's daf; I do not believe that I would have been able to decipher the Gemara without Steinsaltz's direction.

It is so stunningly clear to me that I am a beginner in the study of Talmud.  Today that reminder came early in the daf.  The rabbis debated about the origins of the measurements used.  Of course, I should have known!  The rabbis did not pull "10 handbreadths in height over five cubits length", for example, out of the air.  This was not a measurement chosen because it is experienced as an easy slope to climb, and thus people would not avoid that hill when walking within their eiruv.  Instead, this is based on Torah direction!  Every word describing the construction of the Tabernacle is a clue directing us as to how we are to create proper eiruvin.  Every measurement, every word is there for a purpose (beyond that original reason of building the Tabernacle).  To those who have learned Talmud for years, this must go without saying.  For me, I suddenly gasp when I read those notes that remind me of the depth and breadth of the rabbis knowledge and creative interpretation regarding the construction of halacha.

Throughout today's daf I was wondering about the expertise required to determine these measurements.  I wondered whether a career existed in antiquity devoted solely to the measurement of Shabbat boundaries.  The practice would require specialized knowledge of these precise and complicated laws.  I was wondering about whether there might exist one surveyor who would train his sons; this one family would be responsible for creating the Shabbat boundaries surrounding various villages and towns.  It would not be a skill required many times for each town - though, with any new houses or population growth, it would make sense that new boundaries might be in order. How often might this measurement be repeated?  At the end of today's daf, we learn that in fact eiruvin must be completed by professional surveyors.  So I was not alone in my thinking.  But who were these surveyors?