Meshech Chochma

Rav Meir Simcha HaCohen of Dvinsk (1843-1926) was born in Lithuania and married at the age of 17. He settled in Bialystok, Poland and learned there. After 23 years there, and many rabbinic offers, he finally accepted the position of rabbi in Dvinsk (a town of Mitnagdim in Latvia). He served in that position for 39 years until his death. In Dvinsk there was also a chassidish rabbi known as the Rogatchover Gaon, author of Tzofnat Paneach, with whom he shared mutual respect. Rav Meir Simcha is best known for writing Or Sameach on the Rambam (as well as on certain masekhtot of Shas, and many teshuvot) and Meshekh Chokhma on the Torah (both seforim are named for mnemonics or amalgamations of his name).

HebrewBooks: https://www.hebrewbooks.org/14061