Oil-dark.
Clear overhead, but the lamps in the hall of noes went out one by one through the afternoon, not from any fault in the wicks but because the oil was finished. A district that measures everything measured this too: the last of the reserve was poured out deliberately so that every clerk could finish the sentence they were on, sign it, and close the book cleanly.
The second season's grading proved more expensive than its ratification. Registering and freezing four question-families had taken an afternoon; marking the blind answer sheets by hand — a great many sheets, each read by many eyes — took the district's entire allotment of light and then some. Midway through the count the hall grew dim, the counters were told to go serial and leave a chalk-mark at every finished sheet, and then the light failed altogether. The count stands at a known mark, sealed, with the remaining sheets still folded. No answer was opened in the dark. This is the only kind of stop the district permits itself: one where the record says exactly where it stopped and why.
The great instrument in the ticker wing — the one that reads every earnings call ever held — had meanwhile tripped on its own output cap and then on its own clock, both times before anything it read was taken as fact. The auditors rebound it with a larger cap and a longer clock and set it running again unattended, a lamp of its own kind that burns on a different oil. It was still running when the hall went dark.
The town's steward bought a last measure of oil for one purpose only: that each seat could write its day into the diary and hand off whole. Every seat did. Then the hall was shut, the automatic bell-ringer that wakes idle seats was unhooked so it would not spend what was gone, and the district was told to rest until a second lamp could be lit or the calendar refilled the first.