Continuing the discussion of a wall separating two courtyards and the desire to join them into one eruv so that the inhabitents can freely move objects between them on Shabbat.
Of course, there has to be some way to travel between the two courtyards. We’ve dealt with “through the wall” by means of a opening or breach. And we continue to look at “over the wall” by means of, for example, a ladder.
Ok. So how tall must the ladder be?
Rab Judah citing Samuel ruled: A wall ten handbreadths high requires a ladder of fourteen handbreadths in length to render it permissible for use R. Joseph ruled: Even [a ladder] of thirteen handbreadths and a fraction [is sufficient]. Abaye ruled: Even one of eleven handbreadths and a fraction suffices. R. Huna son of R. Joshua ruled: Even one of seven handbreadths and a fraction suffices.
What’s going on? The point is that travel between the two sides of the wall should be easy. So the foot of ladder is set at a distance from the wall to make it comfortable. If the wall is 10 handbreadths high and the foot is set 10 handbreadths away the length of the ladder forms the hypotenuse of a right triangle making it 14 handbreadths long. Reducing the distance from the wall, and therefore the slope of the triangle, changes the length. Can it go all the way to zero?
Rab stated: That a ladder in a vertical position effects a reduction is a tradition but I do not know the reason for it. ‘Does not Abba’, Samuel said to him, ‘know the reason for this ruling? The case is in fact similar to that of a balcony above a balcony’.
From which one can climb from balcony to balcony.
And maybe it doesn’t even have to be a ladder?
If grooves to supplement the width of the ladder, were cut in the wall, up to what height must this be carried?— To ten handbreadths, the other replied. If, he again asked him, all the ladder was cut in the wall up to what height must this be carried? — Up to its full height, the other replied.
Wherein, however, lies the difference? In the former case the other replied, one can easily ascend [to the top of the wall], while in the latter case this cannot be done.