Give It a Rest Written December 7, 2008   If your hand has nothing particular to do, perhaps you'll rest it in your pocket.  But not while you're driving a car! An automobile driver's hands are so busy that part of the workload must be assigned to his feet.  They operate two pedals called the accelerator and the brake.  (There was once a third device called the "clutch pedal."  I'm told that it still exists on some cars.  However, it's been a long time since I've personally encountered a clutch, so this may be no more than a rumor.) In the old days, a driver's feet had even more tasks.  His shoes were moving as much as my grandmother's when she was pumping the treadle that powered her sewing machine. For example, look at this photo of a 1959 Oldsmobile similar to the one in which our family took a long vacation trip. To apply the parking brake, the driver doesn't pull a lever as in modern cars.  Instead, he steps on a small pedal with his left foot.  The red light comes on.  To release the brake, he steps on the even smaller "Off" pedal, and the main pedal pops back up. The round button that you see on the floor below the parking brake is the headlight dimmer switch.  Step on it once for bright "high beams," once more for dim "low beams."  In modern vehicles, that function as well has been reassigned to a hand-operated lever. I remember some old cars that had a second such button on the floor.  This was around 1949, when I was a toddler riding in "Daddy's car" and (according to my mother's later recollection) helpfully reporting the changing colors of the traffic signals by calling out "Bop!" and "Go!"  This second button activated the electric starter motor. Back then, getting an engine going was a tricky operation.  With one hand, you  adjusted the carburetor mixture by moving a lever connected to the choke.  Perhaps you also adjusted the distributor timing by moving another lever to retard or advance the spark.  You threw a switch to connect the ignition system to the battery.  With your right foot, you adjusted the throttle by holding the accelerator down partway.  When everything was just right, with your left foot you stepped on the starter button to crank the engine, and it came to life (usually). Nowadays, of course, the car's computer automatically sets all the parameters.  With one hand, you turn a key to connect the ignition and activate the starter.  No foot action is required.  There's no starter button to step on. The other button on the floor, the headlight dimmer, also began to go extinct in the 1950s when General Motors introduced the Autronic-Eye.  By then, my father was a Chevrolet-Oldsmobile dealer, so our family drove "demonstrators" with all the latest gadgets. The Eye was mounted in a futuristic streamlined housing on the dashboard.  The photocell inside looked forward through the windshield.  If it detected darkness out there, it allowed the high beams to operate.  But when it saw the headlights of an approaching car, it politely switched to the low beams. Here's another picture of that 1959 Olds with an Autronic-Eye.  The little black dial on the back of the housing adjusted the sensitivity. Of course, the Eye also might dim the headlights at inappropriate times, for example when it saw a reflective sign.  Therefore, it worked better in the empty spaces of the countryside than it did in the complexities of the suburbs. Also note the thermometer-like display of the Safety Spectrum Speedometer.  It magically changed colors!  Below 35 mph, the visible line was entirely green; above 65 mph, red.  This was achieved with a cylinder (something like this) turning behind a narrow window.  As the cylinder rotated, more of the colored area appeared in the slit. In later model years, Olds returned to the traditional speedometer with a dial and a pointer hand.  But now there was a new feature:  an additional hand on the dial, like an alarm clock.  Theoretically, you set it to the speed limit.  If you drove faster and the speedometer pointer passed the alarm pointer, a buzzer and warning light alerted you.  (Most people set the alarm pointer to 120 mph.) Another miles-per-hour-limiting innovation, introduced to General Motors cars in 1959, also works better in the empty spaces than in the suburbs.  It has fared better over time, however.  I'm referring to the device that automatically maintains a selected speed:  cruise control. At first people were reluctant to trust their driving to this gadget.  It didn't seem safe to allow a computer to control how fast they were going.  They preferred to operate the throttle themselves. My father rather liked it for long trips, however, and he tried to sell the accessory to his customers.  He pointed out that while you're cruising under cruise control, your can relax your feet because they have absolutely nothing to do.  You are no longer required to keep a constant pressure on the accelerator pedal with your right foot for mile after mile. As my father said, "You can put your foot in your pocket!"