Reference for Eruvin 168:2

אמר רב אדא בר אהבה בבאין בני תחתונה דרך עליונה למלאות

for the upper one<span class="x" onmousemove="('comment',' A partition round such a hole, though in relation to the sea it is a suspended one, is deemed to extend downwards and penetrating to the bed of the sea (cf. Supra 12a) and forming a private domain through which the water of the sea may be taken up in buckets to the balcony. In the absence of such a device the movement of water or any other objects from the sea which has the status of a karmelith into the balcony which has that of a private domain is forbidden on the Sabbath.');">⁵</span> but not for the lower one restrictions are imposed on the use of both<span class="x" onmousemove="('comment',' Sc. neither the tenants of the upper balcony may draw water from the sea through the hole nor may those of the lower one throw their buckets into that hole to draw water through it.');">⁶</span> until all their tenants have joined in one 'erub!<span class="x" onmousemove="('comment',' Infra 87b. In the absence of a joint 'erub the hole within the partition remains a mixed domain belonging to two different groups of tenants who impose restrictions upon each other and is, therefore, forbidden to both. Now here it is a case of use by lowering on the part of the tenants of the upper balcony and by thrusting on the part of those of the lower one, and yet it was ruled that both groups are forbidden; how then could Samuel maintain (supra 83b) that access is granted to 'the tenants that can use it by means of lowering'?');">⁷</span> - R'Adda B'Ahabah replied: This is a case where the tenants of the lower balcony come<span class="x" onmousemove="('comment',' By means of a ladder.');">⁸</span>

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