Friday, 5 April 2013

Friday 5th April 1963


"Went to USAF Bentwood [possibly now RAF Woodbridge in Suffolk]. Long journey, about 3/4 hour. USAF base boring. Saw over CBR (Chemical Biological and Radioactive) shelter & saw over Voodoo's [?] had two dinners. Afternoon went to see over lightning a/c. When getting out of cockpit Covell nearly pulled ejector seat handle. Went to 'The Road to Hong Kong'."

Re the question I asked in the April 3rd entry about matching days and dates from 1963 and 2013, there were 13 leap years over the period, each advancing a date 2 days through the week - eg 1st February goes from being a Tuesday in 2000 to a Thursday in 2001. So 13 leap years provide 26 days of advancement. The remaining 37 non-leap years each advance by one day. 37 + 26 = 63 - a multiple of 7, so the days and dates match up.

But are there always 13 leap years in a 50 year span?

I'm regretting this: if I did the same blog next year - 'My 1964' - although it was a leap year itself there would still be 13 intervening February 29ths, so days and dates would match up as far as February 28th. However from March 1st there would only be 12 February 29ths so no match. (February 1st was a Saturday in 1964, and will be one in 2014; March 1st was a Sunday in 1964, but will be a Saturday in 2014.)

A further twist is that some century years are not leap years; 2100 is one for example. There is more on this here; it comes down to the failure of the solar system to keep to nice whole numbers in relations between the  earth's rotational speed, its planetary orbit time and some other rather larger astronomical measures. The 'music of the spheres' turns out to have a pleasing atonality.

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