Reference for Eruvin 173:4
אמר אביי ולדברי ר' חנניא בן עקביא היתה סמוכה לכותל בפחות מג' טפחים צריך שיהא אורכה ד' אמות ורוחבה אחד עשר ומשהו
if the balcony was within three handbreadths from the wall<span class="x" onmousemove="('comment',' Lit., 'it was near the wall by less than three handbreadths'.');"><sup>9</sup></span> it is necessary for its length to be four cubits and for its width to be eleven cubits and a fraction.<span class="x" onmousemove="('comment',' All air space of less than three handbreadths is disregarded (according to the law of labud) and the balcony may, therefore, be deemed to be close to the wall.' By cutting a length of four handbreadths to a depth of one handbreadth and a fraction from the width of the balcony on the side adjacent to the wall so as to leave on either side of its length margins of ten handbreadths, the area of the hole would be four handbreadths by (three minus a fraction and one and a fraction is) four handbreadths, and it would be surrounded on three sides by a border of (eleven handbreadths and a fraction minus one handbreadth and a fraction on the side opposite the wall, and (24 - 4) /2 handbreadths on the two sides of the length of the balcony =) ten handbreadths and on the fourth side by the wall of the house. The border is regarded as bent and extended downwards and morning with the wall a private domain between the water and the balcony.');"><sup>10</sup></span> If it was upright<span class="x" onmousemove="('comment',' Standing on its width on a projection from the wall at a distance of four handbreadths with its length rising vertically upwards.');"><sup>11</sup></span>