Page:Popular Science Monthly Volume 90.djvu/262

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Playing Checkers with Electric Lights

Do you want to draw a crowd in front of your place? This bulletin-board game will do it

���Red and green lights are used for checkermen and a white light for a king. There are one

thousand nine hundred and twenty lamps displayed upon the board and one thousand and

twenty-four in the checker squares. About sixty thousand variations may be shown

��ANTHONY NELSON of St. Paul, /-\ Minnesota, is the inventor of a board which plays checkers and other games automatically. When the board is used for playing checkers it is capable of showing sixty thousand or more variations. The games or records are worked out on sheet brass and then placed on a cylinder which revolves slowly, requiring twenty- five minutes to make one revolution. The time required for each game is about eight minutes.

The operation of the board may be described as follows : On the surface of the brass sheets is a series of grooves to con- form with the particular checker game being played on the board. Riding on the surface of these records, which are not unlike the records of the old-time music boxes, are ninety-six arms of a non- conducting material. On the underside of the arms is placed a runner or needle on a

��slant. These runners or needles drag on the surface of the cylinder as it revolves.

Each arm is pivoted at one end. On the upper edge the conducting bar is secured with the contact point at the free end. As the cylinder revolves the runners engage with grooves on the record, raising or lowering the arms. When the arms are raised the circuit is broken and the checker squares controlled by those arms are darkened. At the contact point is a groove extending longitudinally across the terminal board. Mercury is used to insure a perfect electrical circuit, as any failure of the lamps to light on the board would spoil the effect of the game. It requires three arms to control each square on the checker board.

The color scheme is red and green lights for the checkermen, and a white light for the king. When the king is in play a letter "K" with a light background is displayed at the end of the cylinder. Anyone with

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