mdmd(5), assorted notes:

[Brian D. McCary]

148.6 'hornetting sphere' - ie, of lead, the bullet, whizzing by Dixon's ears with
the humming drone of a hornet.  Since the bullet will be moving below the
speed of sound for most of it's flight, the buzzing would be audible just
before the impact (like the V1) but only for a few milliseconds, leading to
the old adage that you never hear the one that gets you.

150.5 'Meridien' Fr name for a type of sofa - note also that meridian is a great
circle, or longitudinal line.  Just as St. Helena is due south of England, Cape
Town may well lie due south of France.  I don't have an atlas here, but 
what longitude is Paris, and what longitude is Cape town?

162.28 'Nawabheit'?  - heit is a suffix meaning qualtity of or -ness
(ie, Krankheit = sickness, Gesundheit = healthfulness) so I read this
as the essense of Nawab.  Not knowing what Nawab meant, I guessed it to
be a german form of Nabob.  Thus, Deiter was "promis'd travel,
adventure, dusky Maidens, and won Day, Nawabheit....", ie, eventually,
his own lordship over his own little dominion.  Especially significant
here:  Clive *had* achieved Nabobness.  (Bonus question: if TRP has been
thinking about this and researching it since the sixties, what are the
chances that Clive Mossmoon was named for Clive of India?)

160.7  " "Two distinct nations, in a state of mutual mistruxt, within
ten miles compass" Just thinking of how close together were Washington
DC and Richmond Virginia, the two captials of the US Civil War." "
In fact, DC itself *is* exactly ten miles by ten miles square, or was
before the Civil war.  The portion lying in Virginia was taken 
back by Virginia as part of the Secession (I think) resulting in the
less geometrically simple shape we have today.  

164.27 ""down into the floor of a ruin'd ebony forest, where among
fog-whisps and ancient black logging debris polished by the Wind...""
This could also be a remenant of the time spent in the Northwest 
during the writing of Vineland.