The Self-Adjusting Mystery Clock

RAY: This puzzler was sent in by a fellow named Mark Sylvia.

Here it is:

It used to be that, when we changed into or out of Daylight Savings Time, you had to manually change all the clocks and appliances in your house.

Now many of them are wired into sources that change them for us. So, for example, you change your wall clock and your microwave clock, but your computer, your cell phone your cable TV clocks automatically show the newly changed time without you having to do anything.

There is, however, a certain clock in my house that is not wired into anything. In fact, it runs on a battery, and it reads correctly all the time without my having to change it every spring and fall at the time changes.

The question is, how does it do this?

Think you know? Drop Ray a note!

[ Car Talk Puzzler ]