Myst Island -- Dentist chair

You are sitting in the dentist chair, with the visor down and the light off. Before you is a way to enter dates. What is this a time machine?

I change the date, but the time still seems to be the present.

Where to I find the dates to enter.

I know the dates, but what's it mean?

Go back to Myst Island -- The building with the dentist chair.