What box?

[foxmoth at qnet.com]

--- In HPFGU-OTChatter at y..., "Amy Z" <aiz24 at h...> wrote:
> > Can someone explain the origins of the phrase "thinking 
> Dear Mr. Anglia,
> 
> I think the box is the elder brother of the envelope, as in 
"pushing 
> the envelope."

Actually, "the envelope" has to do with engineering. Airplanes 
function within certain limits of airspeed, g forces, etc.  These 
form "the envelope" Since this is not an exact science, 
aerospace engineers provide a margin of safety by designing 
the airplane to perform somewhat beyond the published limits. 
Pilots are aware of this, and some will try to get more 
performance out of their craft than it is officially capable of. This 
is the  risky practice of "pushing the envelope."

Pippin