A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Date: 2016 Jul 9, 16:17 -0700
I would not have noticed it, but now that you mention it, I don't think one can add what is already there. So, the additional second can only be inserted AFTER the 60th second, which is at 00:00:00.
But then, I already don't understand what it means to "add a second to a clock". This metaphor suggests that a clock is something like an old fashioned gas meter or telephone that I have to feed a coin every second to keep it happy. But what if my clock is a dripping water faucet, where a drop is coming out every seond? I have to add nothing. On the contrary, I get one more drop out.
Just as an aside, I find it comical that the USNO sees a need to convert the epoch into EST. People who have to worry about leap seconds really should not set their clocks to EST. They probably do that for internal administrative purposes. Somebody has to sit at the Master Clock (which hopefully shows UTC) to press the INSERT button at exactly 7 p.m. EST. That representation is significant for whether he gets paid overtime or not.