"where's the device to speed up or slow down the passage of time!?"
godzilla & the elasmosaurus as time travelers.
This one is quick and neat: charged with changing clock speeds. For some reason I always figured that analog clocks had little dc, pager-type motors in them. I was proved wrong. The quartz-clocked copper coil is pulsed at regular intervals, turning something akin to a miniature top. This "top" is the rightmost gear; teeth on top, magnet on the bottom. The coil itself has a "fork" which surrounds the +/- poles of the top, therein turning it without touching it. This near frictionless drive is why this motor lasts so long and so reliably!
However, it was designed to run at a certain speed. So there are certain speeds that the gearbox rejects, and others that ring true. These "usable" speeds were found by hooking up a function generator to the coil. The rest was done with a 555 generated pulse, which was rigged to run at the "happy" speeds. So in effect, we're bypassing the very regular crystal oscillator with the 555.
^^a giant 555 footstool! source:evilmadscientist
And in case you don't have the most endearing 555 source ever, here it is!:
Forrest Mims is a personal hero, so buy the book if you get the chance; it's better on pulp.
thats it for now!