[LEAPSECS] Testing computer leap-second handling

Rob Seaman seaman at noao.edu
Fri Jul 13 20:16:45 EDT 2012

Tony Finch wrote:

>>> DST exists because people care more about the time of sunrise than the time of noon.

Poul-Henning Kamp wrote:

>> Sunset actually, but yes.

Tony Finch writes:

> The reason I say sunrise is because DST reduces the time variation of sunrise and increases the variation of sunset. It is a quantized approximation to counting hours from sunrise.

An interesting exchange, thanks. Viewing it this way raise issues of quantization noise (the ubiquitous square-root of one-twelfth). Perhaps what DST needs is a scheme for subtractive dithering.

> Remember also Ben Franklin's complaint about Parisians wasting early morning light.

Ben was joking, of course, but as you say the focus was on sunrise:

"One, indeed, who is a learned natural philosopher, has assured me that I must certainly be mistaken as to the circumstance of the light coming into my room; for it being well known, as he says, that there could be no light abroad at that hour, it follows that none could enter from without; and that of consequence, my windows being accidentally left open, instead of letting in the light, had only served to let out the darkness…"

His proposed regulations applied at both ends, however:

- "First. Let a tax be laid of a louis per window, on every window that is provided with shutters to keep out the light of the sun."

- "Second. […] let guards be placed in the shops of the wax and tallow chandlers, and no family be permitted to be supplied with more than one pound of candles per week."

- "Third. Let guards also be posted to stop all the coaches, &c. that would pass the streets after sunset, …"

- "Fourth. Every morning, as soon as the sun rises, let all the bells in every church be set ringing; and if that is not sufficient?, let cannon be fired in every street, …"

Maybe the real problem with DST is that it was never fully implemented as conceived:



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