Eiruvin 83a, b

Today's daf was like walking through a maze of mathematical equations that I'd never seen before.  The rabbis were attempting to answer some of the questions I posed yesterday regarding measures and amounts.  They defined many terms in relation to each other, which was not particularly useful to my understanding.  

Occasionally the rabbis offered a measurement that held some meaning for me - like the size of an egg bulk without the shell.  But then they would speak about 144 egg bulks versus 173 egg bulks, which became confusing again.  Because I did not push myself to follow their calculations, it was almost impossible to understand the rabbi's reasoning.

It turns out that there are three sets of values that can be applied to any of the units used to measure.  One is the wilderness measure, one the Jerusalem measure, and one the Tzippori measure.  Each of these represented a place and time where power was amalgamated.

In 83b, the rabbis look at balconies and courtyards: at what height and at what distance from the balconies can residents in the balconies claim use an independently standing post on Shabbat when there is no eiruv?  It seems that most agree that the object would have to be over 10 handbreadths high and closer than 4 handbreadths to the balcony.  Otherwise the object would be used only by those who reside by the courtyard.

The modern version of today's daf would involve city planning, zoning, building codes, and a wide range of measurement calculation.  My knowledge of modern city planning is limited, and so this learning is truly a stretch for me.  But it was interesting to imagine the rabbis sitting around a table, doing and redoing their calculations over hundreds of years, checking and rechecking the values and their significance.