MISHNAH. SABBATH LIMITS MAY BE MEASURED ONLY WITH A ROPE OF THE LENGTH OF FIFTY CUBITS NEITHER LESS NOR MORE;
The rabbis discuss what precisely this rope is. And why it can only be 50 cubits long.
AND A MAN MAY MEASURE ONLY WHILE HOLDING THE END OF THE ROPE ON A LEVEL WITH HIS HEART.
So it is long enough to be stretched between two people who hold it at the same level. There is some recognition that some ropes will be stretched slightly more than others, but the attempt is to be as precise as possible.
IF IN THE COURSE OF MEASURING THE SURVEYOR REACHED A GLEN OR A FALLEN WALL HE SPANS IT AND RESUMES HIS MEASURING; IF HE REACHED A HILL HE SPANS IT AND RESUMES HIS MEASURING; PROVIDED HE DOES NOT GO BEYOND THE SABBATH LIMIT. IF HE IS UNABLE TO SPAN IT — IN CONNECTION WITH THIS R. DOSTAI B. JANNAI STATED IN THE NAME OF R. MEIR, I HAVE HEARD THAT HILLS ARE TREATED AS THOUGH THEY WERE PIERCED’.
The rabbis give some detail on how this is accomplished:
it may be inferred that if he is unable to span it he proceeds to a position from where he is able to do so and, after spanning it, he makes the necessary observations [whereby he is enabled to locate the point on the far side] that is in a straight line with his original line of measuring and then he resumes [his measurements in a straight line] — Thus we have here learnt what the Rabbis have taught elsewhere: If in the course of measuring the measuring rope reached a glen, the surveyor may span it if he can do so with a rope of fifty cubits, but if not, he proceeds to a position from where he is able to span it and, having spanned it, he makes the necessary observations [whereby he is enabled to locate the point on the far sides that is in a straight line with his original line of measuring] and then he resumes his measuring.
If the glen was a crooked one it is pierced in an upward, as well as in a downward direction. If it reached a wall we do not say: ‘Let the wall be bored through’; its thickness rather is estimated and the measuring continues.
Yet, with all this attempt at precision, you can imagine that there would be some variation. You would be right. Multiple measurements might be made. What if they don’t agree?
IF THERE WAS A GREATER DISTANCE FOR ONE AND A LESSER DISTANCE FOR ANOTHER, THE GREATER DISTANCE IS OBSERVED.
FURTHERMORE, EVEN A BONDMAN AND EVEN A BONDWOMAN ARE BELIEVED WHEN THEY SAY, THUS FAR IS THE SABBATH LIMIT’, SINCE THE SAGES DID NOT ENACT THE LAW IN ORDER TO ADD RESTRICTIONS BUT IN ORDER TO RELAX THEM.
This is in keeping with the general principle “that you may live by them” (Lev. 18:5) – the law should be liberalized! Or at least not be onerous.