Dead Reckoning

[Laurence Horn]

>Is "dead on" related to "dead reckoning"?
>
>Recently I've seen "dead on" in a number of newspaper articles (as in
>Bob Woodward's tribute to Katharine Graham in Monday's Washington Post:
>"For two hours she then proceeded with a brilliant summary and series of
>often-hilarious, dead-on anecdotes about the leaders...") although maybe
>I'm just now noticing.
>
>Avi Arditti

There's also "dead red", "dead spit", "dead to rights", etc., all
apparently corresponding to AHD4's sense 12c, 'exact' and possibly
its cousins:

12a. Sudden; abrupt: a dead stop.
b. Complete; utter: dead silence.
c. Exact; unerring. the dead center of a target.

I'm not sure how this sense or bundle of senses derives from the
standard (= 'no longer alive') one, although speculation is rife.
Anyone?

larry