Brewster's Factor - was :Trouble running programs

[Laura Creighton]

> Bernard Yue's sig is:
>
> There are three schools of magic.  One:  State a tautology, then ring
> the changes on its corollaries; that's philosophy.  Two:  Record many
> facts.  Try to find a pattern.  Then make a wrong guess at the next
> fact; that's science.  Three:  Be aware that you live in a malevolent
> Universe controlled by Murphy's Law, sometimes offset by Brewster's
> Factor; that's engineering.
> 
> So far as I can remember, there is not one word in the Gospels in
> praise of intelligence.
>                 -- Bertrand Russell

I wanted to know what Brewster's Factor was.  I found out that the first
part of the quote -- the bit that ends with Engineering should be
attributed to Robert A. Heinlein (from The Number of the Beast).  But
the only Brewster Factors I can find have to do with polarised light,
or English Chrisitian Revivalist Victorian political parties, neither
of which I suspect is what I am looking for.  Any ideas?

Laura Creighton