The Self-Adjusting Clock

Apr 11, 2020

RAY: It used to be that when we changed into or out of Daylight Saving 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, and 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?



RAY: At my house on the Cape I have a tide clock--and the tide doesn't care whether it's Daylight Savings Time or not. This is an analog clock that has only one hand, the hour hand. It runs slower than a normal clock because the tides don't come at six-hour intervals. High tides are anywhere from 12 hours and two minutes apart to 12 hours and 50 minutes apart.

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