Reference for Shabbat 15:6
אמר עולא עמוד תשעה ברה"ר ורבים מכתפין עליו וזרק ונח על גביו חייב מ"ט פחות משלשה מדרס דרסי ליה רבים משלשה ועד תשעה לא מדרס דרסי ליה ולא כתופי מכתפי תשעה ודאי מכתפין עילויה
mouth downwards, [and throws it], then if it is a shade more than seven [in height] he is liable; if seven and a half, he is exempt.<span class="x" onmousemove="('comment',' It is a principle that the walls of an object are regarded as extending beyond its opening down to the ground itself as soon as that opening comes within a shade less than three handbreadths from the ground. V. Glos. s.v. labud. Hence, when this overturned bin, which is a shade more than seven in height (and certainly if less), enters within just under three handbreadths from the ground and is regarded as already resting on the ground, the whole is within ten from the ground, and therefore he is liable. But if it is slightly taller than this it is partly above ten; hence there is no liability. ');"><sup>6</sup></span>