Revs = Spedometer bouncing?

Riddle me this:

While doing some carb tuning this weekend, I came across the following
phenomenon:  When I revved the engine briefly, to about 4500rpm, I noticed
that my spedo needle fluctuated between 2-5 mph.  What is going on?  I
thought that the cable was connected to the driveshaft assembly.  My car was
definitely not moving, the wheels were chocked.  (Now where did that cat
go?)

Regards,

Charles
'74 Midget
'68 Sprite
Bloomfield, NJ
cdsorkin@ix.netcom.com
"How about we duck inside for a Hen?"