# [time-nuts] Harrison's birthday

Tom Van Baak tvb at LeapSecond.com
Tue Apr 3 20:41:05 EDT 2018

```Jim,

The Harrison google doodle is attached for those that missed it [1].

1) One alert reader pointed out that the clocks are stopped. Google is capable of clever JavaScript animations, so the least they could do is have the clocks in motion. It would be especially interesting to see the famous "grasshopper escapement" in action. Well, there's youtube for that.

2) It might even be useful if the animation showed the clocks with the correct time. UTC at a minimum. Or local time, since google likely has a good idea what timezone you are in.

3) The artist followed the clock face marketing trick of using ~10 minutes after 10 o'clock. That creates symmetry between the hour hand about -60 degrees (left of center) and the minute hand about +60 degrees (right of center).

Some of you realize that the hour hand is exactly -60 degrees only at 10:00, but by the time the minute hand gets to +60 degrees the time is now 10:10. And by then, the hour hand has moved further clockwise (yes, it's the one time when using that adjective is redundant) to -55 degrees so you now have overshot the magic moment when the two hands are truly in symmetry.

You can google the math puzzle of when exactly after 10 o'clock the hands are in pure symmetry [2]. The magic moment occurs at +/- 55.385 degrees which is 10:09:14 AM/PM. If you want it to the nanosecond, then 10:09:13.846153846 is your answer. And this happens twice a day so even if you miss it, you get more chances.

4) Now that you know all of this, look again at the google cartoon. Note that neither the hour hand nor the minute hand is correct. The hour hand is a but too far ahead for 10:09, and the minute hand is a bit too far behind for 10:09. You just can't trust the internet anymore...

/tvb

[1] Doodles:

[2] Math clock puzzles:
https://www.fq.math.ca/Scanned/21-2/monzingo.pdf
https://www.quora.com/At-what-time-are-the-hour-and-minute-hands-at-equal-distance-from-the-6-hour
https://ldlewis.com/hospital_clock/document/Timely.encounter.abr.cmplt.pdf

----- Original Message -----
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Monday, April 02, 2018 9:19 PM
Subject: [time-nuts] Harrison's birthday

> Google reminds us that 3 April is Harrison's birthday..
>
> https://en.wikipedia.org/wiki/John_Harrison
>
> Interesting he (depending on your calendar) was born and died on the
> same day.  And, interesting he died in 1776, which is of some
> significance in the US.
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