Reference for Eruvin 67:4
ואמאי הכי נמי נימא הואיל ויכול לנטותו ולהביאו לתוך עשרה א"ר ירמיה הכא במגדל מסומר עסקינן
at a height] above ten handbreadths [from the ground;<span class="x" onmousemove="('comment',' Though the man could not carry the 'erub from its place to his abode, on account of the public domain which intervened between his private domain and that in which the 'erub lay (cf. Shab. 96a) he could well descend to the level where the 'erub was deposited and consume it there, since in respect of 'erub and 'abode' all space above ten handbreadths from the ground is regarded as one and the same domain.');"><sup>10</sup></span> but if it lay at a level] below ten handbreadths [from the ground]<span class="x" onmousemove="('comment',' If the cote or turret, for instance, had several compartments one above the other, and the 'erub lay in one of the lower ones.');"><sup>11</sup></span> his 'erub is ineffective.<span class="x" onmousemove="('comment',' Since such a place has the status of a karmelith from which it is forbidden to carry the 'erub to the top of the cote or turret on account of the public domain that intervened between them. Should the man descend to the level of the 'erub to consume it there, he would be leaving the domain of his abode for another domain which is contrary to the requirement that the 'erub must be in a positioned from which it can be taken to the abode and eaten there.');"><sup>12</sup></span> but why?<span class="x" onmousemove="('comment',' Should an 'erub below a level of ten handbreadths be ineffective.');"><sup>13</sup></span>