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Eruvin 56

ERUVIN 56 - was generously dedicated by an anonymous donor in Los Angeles.


The Gemara quotes Shmuel who makes an important statement about the seasons of the year. Shmuel says that the four Tekufos of the year are exactly 91 days and 7 1/2 hours long, which means that the year is 365 days and 6 hours long (91 days and 7 1/2 hours X 4). Consequently, the time of day that each Tekufah occurs will be 7 1/2 hours later in the day than the previous one. How accurate is Shmuel's measurement according to present-day calculations?

Julius Caesar, in the year 3714 (46 B.C.E.) arranged a *solar* calendar, the first calendar based on the earth's relationship with the position of the sun, which is very similar to the one used by the modern world today. At that time, his astronomers advised him that the solar year is exactly 365 1/4 days (365 days and 6 hours), the same as Shmuel's calculation. However, in truth this figure is inaccurate; it is a bit too long. The true solar year is 365 days, 5 hours, 48 minutes, and 46 seconds. Shmuel's calculation was off by some 11 minutes per year, which means that with the passage of time, the actual solar year lags behind Shmuel's year. The equinoxes and solstices slowly migrate through the calendar with the passage of time; every 128 years the equinoxes and solstices arrive one day too early.

At a later time, the astronomers noted that they were slightly off and corrected the length of the year to 365 days 5 hours, 55 minutes, and 25 seconds, cutting out about half of the 11 minute discrepancy between Shmuel's year and the actual year. Rav Ada, a third century Amora, recalculated the Jewish lunisolar calendar based on this calculation and organized it into the present 19-year cycle, which has as leap years the 3rd, 6th, 8th, 11th, 14th, 17th, and 19th year of the 19-year cycle. This was done in order that the lunar year, divided up among those 19 solar years, will average out to the length of the solar year mentioned, and thus every 19 years the lunar and solar years will meet.

(NOTE: In 1582 C.E., the non-Jews, not wanting the summer months to fall during winter and the winter months to fall during summer, modified the Julian calendar and adopted a new version called the Gregorian calendar. The first change they made to the calendar was to cut out the 11 days that were mistakenly added to the year due to the miscalculation of the Julian astronomers. (The day after September 3 that year was not September 4, but September 15.) They also adjusted the calendar to by subtracting one leap year every 400 years. This means that they worked with a year of 365 days, 5 hours, 49 minutes and 12 seconds -- which is still off by approx. 26 seconds, but close enough for most practical purposes. At the time, the we instituted *no* parallel changes to the Jewish lunisolar calendar.)

In the final analysis, we follow Rav Ada's calculation in our lunisolar calendar, breaking it into a 19-year cycle. However, for the Halachos which depend on the Tekufos, such as when to say the prayer of "v'Sen Tal u'Matar" in Galus and when we recite Birchas ha'Chamah, we rely on Shmuel's calculation. ("V'Sen Tal u'Matar" in Galus is added in Shemoneh Esreh starting 60 days after the autumnal equinox, and Birkas ha'Chamah is said on the day of the vernal equinox every 28 years, as calculated through Shmuel's calculation. This is why "v'Sen Tal u'Matar" is said in Galus beginning from the 5th or 4th of December, depending on whether the following year is a leap year. This date will not change after the year 2000, since that year is not affected by the Gregorian calendar.)

Dr. Norman Bloom of Miami, Florida, points out that since we are working with two different solar calendars, the time when Jews in Galus start saying v'Sen Tal u'Matar will migrate towards the summer even faster than the spring festivals will migrate towards the summer. This means that eventually, the time to start saying "v'Sen Tal u'Matar" will catch up to Pesach, and the first day to say "v'Sen Tal u'Matar" coincide with day on which we stop saying it! Fortunately, we will not encounter this problem for another approx. 42,000 years, which will be long after the Ge'ulah will have come and all of the Jews will be living in Eretz Yisrael.

QUESTION: RASHI (DH v'Ein Tekufah Mosheches) offers a Siman (a mnemonic) "Siman l'Chezyo AZ'CH GY'CH VA'CH TD'CH." This Siman seems totally out of context, and its meaning is evasive. (The Bach in fact deletes it from the text of Rashi.) What could it mean?

ANSWER: MENACHEM MESHIV NEFESH explains that the Siman is out of place, and it should appear instead at the end of Rashi, DH v'Ein Tekufas Tamuz. There, Rashi discusses the hours of the day in which each of the four Tekufos occur, offering another Siman, "AZG'Y VAT'D" as a mnemonic. This means that if Tekufas Nisan falls out in a given year in the first hour (*A*lef), then Tekufas Tamuz of that year will be in the seventh hour (*Z*ayin), Tekufas Tishrei will be in the third hour (*G*imel), and Tekufas Teves will be in the tenth hour (*Y*ud). The next four letters, "VAT'D," represent the hours in which the Tekufos will fall the following year: Tekufas Nisan in the sixth hour (*V*av), Tekufas Tamuz in the first hour (*A*lef), Tekufas Tishrei in the ninth hour (*T*es), and Tekufas Teves in the fourth hour (*D*ales).

However, this Siman only gives us the whole hour in which the Tekufos fall, but it does not tell us when exactly during those hours they fall. Some of the Tekufot will occur on the half hour, while others will occur on the hour. This is the purpose of the next Siman. The words "Siman le'Chatzayos" (in our texts there is a printing error, the word " le'Chatzyo" should read "le'Chatzayos," as it appears in earlier printings) means "a Siman which includes a note as to which Tekufot occur on the half hour.

This Siman, "AZ'CH GY'CH VA'CH TD'CH" tells us that when Tekufas Nisan falls on the first hour (*A*lef), then Tekufas Tamuz will occur on the seventh and a half hour (*Z*ayin *Ch*atzi" -- seven and a half). Tekufas Tishrei will be on the third hour (*G*imel), and Tekufas Teves will occur on the tenth and a half hour (*Y*ud *Ch*atzi). Thus, this Siman is exactly the same as the previous one, except this Siman inserts "Ches" after every second number in order to show that the Tekufah will be on the half hour and not on the hour.


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