As far as a pioneer in baseball in New York City, many would claim Ruth, Gehrig, Mantle, Mays, but arguably no one had a greater influence than Alexander Cartwright. Following the introduction of the New York Knickerbocker Base Ball Club, Cartwright and a committee from his club drew up rules converting this playground game into a more elaborate and interesting sport to be played by adults. Such advancements included foul territories, three strikes per batter, flat bases and nine players in the field. Cartwright would pass in 1892, with Major League Baseball introducing him into the Hall of Fame in 1938 for his countless advancements in the game. Due to his "late" adding to the Hall and early passing, Alexander Cartwright signatures remain one of the hardest to obtain of all the Major League Baseball Hall of Fame members, and may be the most influential. Offered here is an ULTRA-RARE 3" x 7" off-white envelope twice signed & hand written by Alexander Cartwright regarding payment for a mortgage to M. Paiko. Overall in fine condition with discoloration & frayed edges. Adding to the allure of this rare item is it was once part of Barry Halper's collection, regarded as one of the finest Baseball collections in the World! Authenticated & encapsulated by PSA/DNA.