Automobile safety instrument

Claim 1

A COMBINED VEHICLE SPEED AND SAFE STOPPING DISTANCE INDICATOR COMPRISING OPAQUE MEANS DEFINING A SUBSTANTIALLY HORIZONTALLY DISPOSED SLIT, AN ELONGATED DRUM ROTATABLY MOUNTED ON A SUBSTANTIALLY HORIZONTAL AXIS ADJACENT TO AND SUBSTANTIALLY PARALLEL WITH SAID SLIT, MEANS DEFINING A SUBSTANTIALLY LINEAR SPIRAL ABOUT THE CIRCUMFERENCE OF SAID DRUM, MEANS DEFINING AN AT REST POSITION OF SAID DRUM, MEANS RESPONSIVE TO THE SPEED OF THE VEHICLE FOR ANGULARLY DISPLACING SAID DRUM TO AN ANGULAR POSITION LINEARLY RELATED TO SAID SPEED, AT WHICH POSITION SAID SPIRAL IS VISIBLE THROUGH THE SLIT AT A DISTANCE FROM ONE END OF SAID SLIT LINEARLY RELATED TO SAID SPEED, A LINEAR CALIBRATED SCALE ALONG SAID SPLIT COOPERATIVE WITH THE VISIBLE PORTION OF SAID SPIRAL TO INDICATE SAID VEHICLE SPEED, A PLURALITY OF BODIES DEFINING A NON-LINEAR SPIRAL ABOUT THE CIRCUMFERENCE OF SAID DRUM, ONE OF SAID BODIES BEING VISIBLE THROUGH THE SLIT IN PROXIMITY TO SAID ONE END WHEN SAID DRUM IS IN ITS AT REST POSITION, EACH OF THE OTHER OF SAID BODIES BEING VISIBLE THROUGH THE SLIT AT A DISTANCE FROM THE ONE END OF SAID SLIT LINEARLY RELATED TO THE SAFE STOPPING DISTANCE OF SAID VEHICLE AT A RESPECTIVE INDICATED VEHICLE SPEED, AND A SECOND LINEAR SCALE CALIBRATED IN LENGTHS OF SAID BODIES AND COOPERATIVE WITH SAID BODIES TO INDICATE THE SAFE STOPPING DISTANCE IN TERMS OF VEHICLE LENGTH.