1909 Spalding’s Official Base Ball Guide. – Page 351
Two or three years ago Base Ball critics in the East and West began to agitate the question of signaling by the umpires to announce their decisions.
At first the judges of play did not want to signal. They thought it detracted from their dignity to go through a dumb show resembling the waving of the arms of a semaphore.
That did not deter the Base Ball critics from their stand. With good-natured persistence they urged upon the umpires the necessity of the new idea, and by and by the officials of the league took up the subject and suggested that it would be worth a trial.
It was finally experimented with and has been one of the very best moves in Base Ball as a medium of rendering decisions intelligible, and now there is not an umpire but uses him arms to signal. If he did not, two-thirds of the spectators at the immense crowds, which have been patronizing Base Ball for the last two years, would be wholly at sea as to what was transpiring on the field, except as they might guess successfully.
Right arm in the air with one finger pointing to the sky can be read for a long distance as a strike. When two fingers are upraised the crowd knows it is two strikes, and it doesn’t care to hear much about the third strike, because the movements of the batter will certify to that.
The left arm is used to signal the number of balls when it is necessary to do so. Some umpires never use the arm when a ball is called, and by refraining from doing so the crowd understands that it is not a strike. When the clamor is deafening and the pitcher calls for the number of balls the left arm is raised with as many fingers extended as balls have been called against the batter.
Almost every umpire has a characteristic motion for calling the runner safe. As a usual custom, however, the arms extended with the palms of the hands turned down signify that the runner has reached the base legally.
When calling a runner out most of the umpires use a sweeping motion of the arm which signifies that the unfortunate player is to return to the bench.
An umpire may signal that a runner is safe, and on the very instant that he gives the decision the baseman may drop the ball. All the staff of the major leagues are quick to reverse the signal from a motion to leave the base, to the other motion of dropping the arms quickly with the palms of the hands down. It is understood at once, both by players and spectators.
Even the older umpires, who were more loath to give their consent to the new system on the field, are now frank enough to admit that it has been of invaluable assistance to them in making their decisions understood when the size of the crowd is such that it is impossible to make the human voice carry distinctly to all parts of the field.
Illustrations are appended showing the signals which are in vogue at the present time.