"He was, however, forced to comply with the "jinx" rule that was then prevalent. The rule was born out of a superstitious belief: If a pitcher was in the process of pitching a no-hitter, you couldn't say so. If you did, you might jinx him and cause him to lose the no-hitter. This also extended to the dugout. The pitcher's team mates were not supposed to discuss the possibility of a no hitter. And they weren't supposed to talk to the pitcher at all.
I still believe in it! (How many perfect series games have been pitched since?) :)