Help with Identifying Special Instrument

Folks,

I had this posted a few days ago from another system, seems it did not get
through. I need your expertise. In our club a flight instrument came up
which baffles us. It is kind of a timer with a mech clock, allows to set an
airspeed on its left side (with a locking thumbwheel) and has an egg-like
shape indication (dented on the right side) with time lines(?) labelled
"miles scale." Inscribed is the text "Gorman Check Pointer" and "Model 150
Pat.Pend. Check Point Sales, Randolph Mass." Not really sure, but should be
1960-1980. All we know is that it was used as an instrument for air rallys
but even our old timers and gurus passed.

Googling on any of those terms also failed. Does anyone know what this is
exactly and how it is supposed to work?

regards

Herbert
Cessna 172 Rocket Rider
LOAV

PS: Email me for pictures of the gadget.