Reference for Eruvin 116:5

התם שאין חוט המשקולת יורד כנגדו הכא בחוט המשקולת יורד כנגדו

but here it is one where it does descend in a straight line.<span class="x" onmousemove="('comment',' The sides of the glen being absolutely unsuitable for walking, its depth, however great, is of no consequence.');">⁹</span> Where the plumb line does not descend in a straight line how much [deviation]<span class="x" onmousemove="('comment',' At the bed of the glen in relation to the edge thereof.');">¹⁰</span> is allowed? - Abimi replied: Up to four cubits; and so learned Rami B'Ezekiel: Up to four cubits.

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