Borough Hall (side-arm pitch in Brooklyn)

A baseball definition was published in the 1943 Baseball Guide and Record Book:
 
“Borough Hall—Side-arm pitch in Brooklyn.”
 
The term refers to Brooklyn Borough Hall and was used by the Brooklyn Dodgers baseball team. The little-used term is of historical interest today.
   
   
24 June 1943, Miami (FL) Herald, “Spotlighting Sports” by Everett Clay, pg. 2B, col. 3:
Diamond Definitions—the vocabulary of words and phrases used to describe incidents, individuals and plays of baseball—is brought up to date in the 1943 Baseball Guide and Record Book.
(...)
Borough Hall—Side-arm pitch in Brooklyn.
 
6 July 1944, The Daily Plainsman (Huron, SD), “Andygrams” by Ford Andrews, pg. 9, col. 7:
If Frank Winters, Armour hurler, lived in Brooklyn, N. Y., and tossed them over the platter for the Dodgers, they’d probably call his side-arm delivery his “Borough Hall Special.” That’s the Flatbush slang for a side-arm pitch.
 
Google Books
The Dickson Baseball Dictionary (Third Edition)
By Paul Dickson
New York, NY: W. W. Norton & Company, Inc.
2011
Pg. 127:
Borough Hall hist. A sidearm pitch in Brooklyn during the period when that borough hosted the Dodgers (Al Schacht, Al Schacht’s Dope Book, 1944).