Reference of Measurements in Halacha: Difference between revisions

* Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is Biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>

! Coin<ref>Gemara Kiddushin 12a</ref>

! Sela

! Dinar

! Maah

! Pundiyon

! Isur

! Prutah

| style="text-align:left;" | Sela

| 1

| 4

| 24

| 48

| 96

| 768

| style="text-align:left;" | Dinar

| 1/4

| 1

| 6

| 12

| 24

| 192

| style="text-align:left;" | Maah

| 1/24

| 1/6

| 1

| 2

| 4

| 32

| style="text-align:left;" | Pundiyon

| 1/48

| 1/12

| 1/2

| 1

| 2

| 16

| style="text-align:left;" | Isur

| 1/96

| 1/24

| 1/4

| 1/2

| 1

| 8

| style="text-align:left;" | Prutah

| 1/768

| 1/192

| 1/32

| 1/16

| 1/8

| 1

#A [[prutah]] is 1/40 of a gram of silver (which is about a few cents). However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]]. <ref>S”A CM 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurei HaMitzvot (Chazon Ish pg 65) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

# A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

# According to Sepharadim, Alot HaShachar is 72 minutes before sunrise.<ref> Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref> Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

# Some hold that Alot is determined degrees below horizon. There are three opinions about the measure of the mil and therefore, there are three opinions of when Alot is:  

## 120 minutes by degrees is 25.9 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

## 90 minutes by degrees is 19.75 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

## 72 minutes by degrees is 15.99 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>  

# Some hold that Alot is determined degrees below horizon. There are three opinions about the measure of the mil and therefore, there are three opinions of when Alot is 120, 90, and 72 zmaniot minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

# Some hold that Alot is determined by 4 mil by fixed minutes. There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:  

## 120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>

## 90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>

## 72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

# Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calcuated 1.25 hours before shekiya like the Gra.</ref>