[LEAPSECS] the leap second in the media

[John Hawkinson]

(chiming in a bit late...)

Tony Finch <dot at dotat.at> wrote on Thu,  1 Jan 2009
at 06:10:59 +0000 in <alpine.LSU.2.00.0901010602100.2395 at hermes-1.csi.cam.ac.uk>:


> Wednesday's PM on Radio 4 included an item about the way the keepers of

> the Big Ben clock handled the leap second. They slowed it down for several

> hours by removing a stack of old coins from a plate near the top of the

> pendulum to lower its centre of gravity. They replaced them again when it

> had lost a seond. Rubber seconds, 19th century style!


This is exactly how Unix systems handle changing the clock!

>From the Solaris adjtime(2) manpage:


DESCRIPTION
     The adjtime() function adjusts the system's  notion  of  the
     current  time  as returned by gettimeofday(3C), advancing or
     retarding it by the amount of time specified in  the  struct
     timeval pointed to by delta.

     The adjustment is effected by speeding up (if that amount of
     time is positive) or slowing down (if that amount of time is
     negative) the system's clock by some small percentage,  gen-
     erally a fraction of one percent. The time is always a mono-
     tonically increasing function. A  time  correction  from  an
     earlier call to adjtime() may not be finished when adjtime()
     is called again.

--jhawk at mit.edu
  John Hawkinson