Edison invents baseball umpire; home plate is insulated with glass insulators

The "Electrical Induction Indicator."

[From the Detroit Free Press]

One element that has contributed largely to Edison's success is the timliness of his inventions. His latest discovery, or more properly speaking, achievement, in practical electricity is an example of this. The device just patented in Washington (No. 49,371) is so timely that it would almost seem to have been brought out purposely during the past week, yet Edison has been working at it for over seventeen months. In his specification he calls it an "electrical induction indicator," which to the uninitiated mind conveys no meaning or purpose. It is in reality an electrical umpire, and the exhibition of it yesterday at Recreation Park in the presence of a few scientists shows it to be by far the most marvelous of Edison's productions. The machine looks like a small upright clock. It is four feet three inches in height and there is a dial at the top six inches square. Two arms of very light and thin vulcanized rubber hang from below the dial and work somewhat similar to the arms of a railway semaphore. These arms are of different colors and are attached to inside mechanism too complicated for description here. The red arm rises to the left, and the black — the natural color of the rubber — to the right. This device is placed behind the plate and in a direct line with it and the pitcher. The plate is of copper, resting on glass insulators, and is connected with the machine by two underground wires, although yesterday the wires lay on the ground, being silk protected. The plate being charged heavily with electricity and being cut-off from the ground by the glass insulators electrifies a column of air immediately above it. When the ball passes through this column the dial records "one strike," as the ball has passed over the plate. If the ball passes to the left, the arm on that side rises, thus recording "one ball" and showing the pitcher on which side he has erred. If the ball goes too high or too low this is also recorded by an ingenious arrangement at the side which shows in feet and inches, and even in the fraction of an inch, if required, the exact height of the ball above the ground at the time is passed the plate. All this is very simple and depends on well-known principles relating to electrical strata of air — the same priciples, in fact, that make telegraphing to moving trains possible, or telegraphing through air currents without wires. The complicted part of the machine is the means by which it determines whether or not a man is out. There are wires to each of the bases and the front dial records the exact time, to the fraction of a second, at which both ball and runner reach the base. Not only is this shown on the dial, but it is permanently recorded on an endless paper ribbon inside, as, indeed, are all the movements of the game. This ribbon, which is taken out at the end of the game, shows by its perforations a complete report of the contest, except as far as the fielding is concerned. This electrical umpire will be surrounded by a strong wire netting, to prevent it being hit by balls or mobbed by a crowd at Washington. Mr. Durant, Edison's traveling agent, says that the inventor expects early next month to have some patents issued by which these recorders can be set up at places miles away from the game, and that they will give a complete record of the struggle as it goes on, the indicators being connected with the electrical umpire on the ground by wires. The cost of each machine will be about $650. They will not be sold out-right, but will be rented for the season at from $150 to $200 a month.