The question is related to geographical issues and I need someone familiar with the topography around Haifa.
You write the following (which is an apparent restatement of the Gemara):
(a) One can also determine Rebbi Nechemya's dusk period by leaving the sun at the top of Mount Karmel, and then going down to Tovel - as he comes up, night will fall.
The sun sets INTO the Mediterranean Sea at Har HaKarmel. So if one is at the top of the mountain when does he start down? At sunset? How long does it take to go from the top of the mountain to the bottom, tovel and come up?
Surely, much more than his shiur is !
Is he at the bottom of the mountain ? Then it's probably less!
I can't find anyone to explain to me the situation and compare it to reality at the mountain in Haifa.
Exactly where is he standing? Where is the sun when he starts to descend?
Your quotation does nothing to elucidate the matter. Any help would be appreciated.
We wrote the following in the Background to the Daf section. It should answer your question.
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12*) [line 19] HA'ROTZEH LEIDA SHI'URO SHEL REBBI NECHEMYAH - That is, although Rebbi Nechemyah gives a very clear Shiur in the Mishnah, the Gemara wants to describe the Shiur in terms of the time it takes to perform a Tevilah, so that people will be able to time their Tevilah to finish before Bein ha'Shemashos (TOSFOS -- according to this explanation, the Gemara is easier to understand if the end of the Tevilah coincides with the beginning of Bein ha'Shemashos, as Tosfos indeed explains. RASHI explains the Gemara according to its simple reading, though, that the end of the Tevilah coincides with the end of Bein ha'Shemashos, and its beginning coincides with the beginning of Bein ha'Shemashos. Nevertheless, the Gemara may be describing the Shiur of Rebbi Nechemyah in terms of Tevilah, for those that want to time their Tevilah to finish before Bein ha'Shemashos begins -- M.Kornfeld) *13*) [line 19] YANI'ACH CHAMAH B'ROSH HA'KARMEL - (The name "Karmel" in this Sugya clearly does not refer to the Har ha'Karmel which lies along the Haifa coast, since the person in our Sugya appears to be watching the sun set to the West of Karmel, and then going to the Mikvah to the East of the mountain. Rather, it is a mountain to the west of Teveryah, from which one can see Lake Kineret to the East, as Rabeinu Chananel explains. This is equally evident from the fact that the well of Miriam is visible from the top of the Karmel, since we know that the well of Miriam is hidden in Lake Kineret.)I, too, had seen the added word by R' Chananel but there are many
difficulties with this explanation.
1. The name Karmel as the name of a mountain at the shores of the
Kinneret is not attested to anywhere in Tanach, Shas or any Midrash. Nor is there any such attestation in any old maps. This statement is a conjecture which has no other support.
2. R' Chanina who is the one providing the illustration regarding Har HaKarmel lived with Rebbe in Beth Shearim / Tzipori not in Teverya. If he had meant a Karmel other than the famous one he most assuredly would have provided some identifier to explain that he is not talking about the very famous Karmel.
3. Your statement "since we know that the well of Miriam is hidden in Lake Kineret" is misleading. The statement about Be'er Miriam comes from the Yerushalmi in Kelayim followed by the various Yerushalmi Aggudos.
Yerushalmi Kilayim 9:3
Yerushalmi Kesuvos 12:3
Vayikra Rabba 22:4 - See Radal here where he wants to amend in Shabbos to "Yeshimon" but I think his reasoning here is faulty since the only reason for the Gemara bringing this "memra" here is as a follow-on to the previous "memra" based on the word Karmel.
Bamidbar Rabba 19:26
Koheles Rabba 5:8
Shoxer Tov 24 - mountain called Nebo; which was in the area called
"Yeshimon"
Tanxuma Xuqas on the posuq (I am not sure about classification whether Bavli or Yerushalmi since he learned from both)
There is no statement about Be'er Miriam in the Kineret in Bavli and as in many cases they may not agree. Obviously, there is no point in
surmising a disagreement if one does not have to. However, you fail to point out that ALL of the Yerushalmi statements that say that Be'er Miriam is visible from a mountain call this mountain "Yeshimon" NOT Karmel.
4. I said that I was not very familiar with the geography near Haifa but I do know Math. The very longest Shiur for a Mil is 24 minutes. R' Nechemiah says that his Shiur is a half a mil. This gives us at the utmost on level ground 12 minutes duration. If we take away the time for the tevilah we are left with approximately SEVEN minutes. What I had asked and you did not answer was for you to show me a mountain - either near Haifa or Teverya - where one could walk from the top to the shores of the sea in just SEVEN minutes ! I don't think the people in the hotels in Teverya can do that from their rooms ! (The difference between Rashi and Tosefes doesn't affect this question.)
5. The very plain language of the Gemara does NOT say that the PERSON is on top of the mountain but that the SUN is on top of the mountain. Rashi may also not mean to say that the PERSON is on top of the mountain but the SUN is on top and gives a general statement that before setting the sun can be seen to be on the top of mountains.
I have, therefore, come up with a explanation for this Gemara which is different than the standard interpretation but in order to verify it I would need to know the geography better. Perhaps I will IYH go there myself. Your explanation is unacceptable to me for the above listed reasons.
1. Your contention with the explanation of RABEINU CHANANEL is correct, in that we do not find any specific reference to a Karmel at the Kineret in Tanach or Shas. Nevertheless, it does not seem impossible that a Rishon like Rabeinu Chananel had some knowledge of some place near Kineret that was referred to as "Karmel."
Furthermore, we do find a number of places in Tanach where the word "Karmel" is used to refer to any fertile, planted hill, and not to a specific mountain in the Haifa region. See, for example, Shmuel I 25:2 and Radak there, Melachaim II 19:23, Yeshayahu 10:18 and Rashi there, Yeshayahu 16:10 and Rashi there, Yirmiyahu 2:7 and Rashi there, and a number of other places. (See also Rashi in Shabbos 3b, DH Ba'i Abaye.) Of course, even in light of these sources, Rabeinu Chananel's explanation here is still a Chidush.
2. Rebbi lived in Teverya for many years (and Rabbi Chanina with him), as we find in Megilah 5b (see Tosfos there) and other places.
3. Thank you for the comprehensive list of sources for the location of the Be'er Miriam.
4,5. The person being Tovel is standing at the bottom of the mountain (this is what we meant in the passage that we sent you from the Background section), and he merely sees the sun at the top of the mountain, as Rashi implies. Also, the Gemara is not saying that the time span of 1/2 Mil passes until he is Tovel; rather it is saying that by the time that he finishes the Tevilah, the time of Rebbi Nechemiah's Bein ha'Shemashos begins (according to Tosfos; according to Rashi, that is when it ends).
Thank you for your comments and elucidations. We would be glad to hear your own interpretation of this Gemara.
Be well and l'Hitra'ot!