Abstract: A computer system is provided for timing contestants on a water race course. A computer interfaces through a card to four switches. A manual and an automatic switch are activated upon the contestant starting the race. Other manual and automatic switches are activated upon the contestant finishing the race. The computer has software which allows the time at which each switch is activated to be recorded and associated with the contestant. The start and finish times are determined by the respective automatic switches unless an automatic switch misfunctions, and doesn't provide a time. In that case, the start or finish time is determined from the affiliated manual switch. The software subtracts start time from finish time to yield elapse time.

Abstract: Holograms, including diffraction gratings, and methods of making them, that reconstruct an image which changes as the hologram is tilted with respect to the viewer and in a manner that images reconstructed from copies made of the hologram in monochromatic light do not have that motion. The hologram is a valuable security device for authenticating documents or objects to which it is attached since it is extremely difficult to duplicate.