| 摘要 |
A computer device for assisting spot bowlers to determine starting position and direction in which to bowl a ball to collide with a predetermined pin or group of pins, comprising two coextensive, rectangular members. On one member, a representation of a bowling lane with appropriate markings is obversely displayed. The other member is transparent and contains a bowling ball indicator that is concentric with the five-pin location spot when the two members are aligned. The invention is calibrated by aligning the two members and for a strike ball tracing a straight line from the starting position of the proper foot to the target over which the ball passes on the transparent member. By adjusting the relative positions of the two members such that the bowling ball indicator approaches the required pin from the appropriate direction, a spot bowler by noting the location and direction of the calibration line will be aided in choosing a starting position and a spot at which to aim the ball in attempting to pick up a spare.
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