Eruvin — Daf 76b

הני מילי בעיגולא אבל בריבועא בעינן טפי

מכדי כמה מרובע יתר על העגול רביע בשיתסר סגיא

ה"מ עיגולא דנפיק מגו ריבועא אבל ריבועא דנפיק מגו עיגולא בעינן טפי מ"ט משום מורשא דקרנתא

מכדי כל אמתא בריבוע אמתא ותרי חומשי באלכסונא בשיבסר נכי חומשא סגיא

רבי יוחנן אמר כי דייני דקיסרי ואמרי לה כרבנן דקיסרי דאמרי עיגולא מגו ריבועא ריבעא ריבועא מגו עיגולא פלגא:

פחות מד' על ד' וכו': אמר רב נחמן לא שנו אלא חלון שבין ב' חצירות אבל חלון שבין ב' בתים אפילו למעלה מעשרה נמי אם רצו לערב מערבין אחד מ"ט ביתא כמאן דמלי דמי

איתיביה רבא לרב נחמן אחד לי חלון שבין ב' חצירות ואחד לי חלון שבין ב' בתים ואחד לי חלון שבין ב' עליות ואחד לי חלון שבין ב' גגין ואחד לי חלון שבין ב' חדרים כולן ד' על ד' בתוך עשרה

תרגומא אחצירות והא אחד לי קתני תרגומא אד' על ד'

בעא מיניה ר' אבא מרב נחמן לול הפתוח מן בית לעלייה צריך סולם קבוע להתירו או אין צריך סולם קבוע להתירו

כי אמרינן ביתא כמאן דמלי דמי הני מילי מן הצד אבל באמצע לא או דילמא לא שנא

אמר ליה אינו צריך סבור מינה סולם קבוע הוא דאינו צריך הא סולם עראי צריך איתמר אמר רב יוסף בר מניומי אמר רב נחמן אחד סולם קבוע ואחד סולם עראי אינו צריך:

מתני׳ כותל שבין ב' חצירות גבוה עשרה ורוחב ארבעה מערבין שנים ואין מערבין אחד

היו בראשו פירות אלו עולין מכאן ואוכלין ואלו עולין מכאן ואוכלין ובלבד שלא יורידו למטן

נפרצה הכותל עד עשר אמות מערבין שנים ואם רצו מערבין אחד מפני שהוא כפתח יותר מכאן מערבין אחד ואין מערבין שנים:

גמ׳ אין בו ארבעה מאי אמר רב אויר שתי רשויות שולטת בו לא יזיז בו אפילו מלא נימא

— This1 applies only to a circle, but where a square2 is to be inscribed within it a greater circumference is required.3 But observe: By how much does the perimeter of a square exceed that of a circle? By a quarter approximately; should not then a circumference of sixteen handbreadths4 suffice?5 — This6 applies only to a circle that is inscribed within7 the square, but where a square is to be inscribed within a circle it is necessary [for the circumference of the latter] to be much bigger.8 What is the reason? In order [to allow9 space for] the projections of the corners.10 Consider, however, this: Every cubit in [the side of] a square [corresponds to], one and two fifths cubits in its diagonal; [should not then11 a circumference] of sixteen and four fifths handbreadths12 suffice?13 — R. Johanan holds the same view as the judges of Caesarea or, as others say, as that of the Rabbis of Caesarea who maintain [that the area of] a circle that is inscribed within a square Is [less than the latter by] a quarter14 [while that of] the square that is inscribed within that circle15 [is less than the outer square by] a half.16 IF THE SIZE OF THE WINDOW WAS LESS THAN FOUR HANDBREADTHS BY FOUR etc. R. Nahman explained: This17 was learnt only in respect of a window between two courtyards but in the case of a window between two houses, even though It was higher than ten handbreadths from the ground, the residents may, if they wish, prepare one ‘erub jointly. What is the reason? — A house is regarded as filled.18 Raba raised an objection against R. Nahman: A window, irrespective of whether19 it was between two courtyards, between two houses, between two upper rooms, between two roofs,20 or between two rooms, must be of the size of21 four handbreadths by four within ten handbreadths from the ground? — The interpretation is [that the limitation22 applies] to the courtyards.23 But was it not stated: ‘irrespective of whether’?24 — The interpretation is that this refers to the prescribed four handbreadths by four’. R. Abba25 enquired of R. Nahman: If an aperture26 led from a room to an upper room,27 is a permanent ladder28 necessary for the purpose of allowing the movement of objects29 or not? Do we apply the principle, that ‘a house is regarded as filled’ only when the aperture30 is at the side but not when it is in the middle31 or is it possible that there is no difference? — The other replied: It is not necessary. He32 understood him33 to mean that only a permanent ladder is not necessary but that a temporary one is necessary. It was, however, stated: R. Joseph34 b. Minyomi citing R. Nahman laid down: Neither a permanent, nor a temporary ladder is necessary. MISHNAH. IF A WAIL BETWEEN TWO COURTYARDS WAS TEN HANDBREADTHS HIGH AND FOUR HANDBREADTHS THICK, TWO ‘ERUBS MAY BE PREPARED35 BUT NOT ONE.36 IF THERE WAS FRUIT ON THE TOP OF IT,37 THE TENANTS ON EITHER SIDE MAY CLIMB UP AND EAT THEM PROVIDED38 THEY DO NOT CARRY THEM DOWN. IF A BREACH TO THE EXTENT OF TEN CUBITS WAS MADE IN THE WALL, THE TENANTS MAY PREPARE TWO ‘ERUBS35 OR, IF THEY PREFER, ONLY ONE,39 BECAUSE IT40 IS LIKE A DOORWAY. IF THE BREACH WAS BIGGER, ONLY ONE ‘ERUB AND NOT TWO MAY BE PREPARED.41 GEMARA. What is the ruling where it42 was not FOUR HANDBREADTHS wide? — Rab replied: The air of two domains43 prevails upon it and44 no object on it may be moved even as far as a hair's breadth. can be inscribed must have, as laid down by R. Johanan, a minimum circumference of twenty-four hand breadths. be no less than twenty-four handbreadths. the area that is required. side of which is equal to (5/7 of its diagonal or 28/5 X 5/7 =) four handbreadths, may be inscribed. laid down in Caesarea seems to bear on the area of the circle and the squares, R. Johanan applied it also to the circumference of the circle and thus required a much bigger circumference than is actually necessary for an inscribed square of four handbreadths by four. their roofs above and, consequently, no movement of objects from one person's roof to that of another is permitted unless a proper ‘erub is prepared. occupied by two residents respectively. The prescribed thickness of four handbreadths, which has no bearing on this restriction since it applies to all walls whatever their thickness, was mentioned on account of the ruling that follows which is applicable only where the thickness of the wall was no less than four handbreadths. A lesser thickness does not constitute a separate domain. break up into two parties for ‘erub. If they do they impose restrictions of movement upon each other. domains.