Gershayim

Why is the name of the trop "gershayim" usually pronounced mil'ra, with the accent on the ultimate syllable (ger-sha-YIM), rather than mil'el, with the accent on the penultimate syllable (ger-SHA-yim)? The word is clearly a dualized form of the name of the trop "geresh", as the symbol for gershayim is merely a geresh adjacent to another geresh, and all other similar dualizations have accents on the penultimate syllable: yaDAyim, ragLAyim, Sh'naSAyim.

In searching for the answer to this question, I was referred to _Chanting the Hebrew Bible: The Art of Cantillation_, by Joshua Jacobson, which I've found to be a wondeful references in answering the "why"s of the ta'amim and explaining how the trop of a passuk reflects its structure.

Dr. Jacobson notes that the trop gershayim is, without exception, found on words that are accented on the ultimate syllable. Therefore, in order to parallel the name of the trop to the words upon which it is found, the trop, too, is purposely mispronounced mil'ra, with the accent on the ultimate syllable. S'fardim, though, solve the problem a different way, by calling the trop "ger'shim", using the basic plural form of the word rather than the dual form, so that the accent does not have to be artifically changed.