[Avodah] Geshem or Gashem?!

[Mandel, Seth via Avodah]

From: Insights Into Halacha <yspitz at ohr.edu>
Sent: Thursday, November 3, 2016 2:57 PM
To: Professor L. Levine
...
> Well, what is the next word? Is it Geshem (with a segol under the letter
> Gimmel) or is it Gashem (with a kamatz under the letter Gimmel)? Which
> is the proper formula?
...
> Y. Spitz
> Yerushalayim
> yspitz at ohr.edu

Far be it for me to stick my head in among all these poskim.

I can only attest to facts: All the all ms. Ashkenaz siddurim that I
have seen (about 30) from the years before printing all have geshem.
I am not claiming what is right or wrong, I am just pointing to the facts.

In addition, for those interested in what the acharonim said, RYBS said
in the name of his father that R. Chaim Brisker said geshem.

Rabbi Dr. Seth Mandel