2026-10-11 — supernaculum

Morning, friend. Sunday. The second Sunday of October — the sun comes up slower than it did last month, the furnace has started making its first annual complaints, and nothing on your calendar is a thing you have to do. Take the long tea.

To supernaculum is to drink to the last drop — not metaphorically, but to the operational standard established at sixteenth-century German and English drinking tables, where finishing a toast meant upending the empty cup over the back of your thumb and showing that no more than a single drop could roll off your thumbnail. Anything larger was a wet-handed shame. The word is medieval Latin super unguem, "upon the nail," and arrives in English in Thomas Nashe's Pierce Pennilesse (1592) with the gloss: "They have in this Country a strange kind of drinking, as namely Supernaculum, that is, when you have drunk, to turn the Cup over, and lightly tap it upon your naile, so that no drop may fall out: and so you drink again." The ceremony drops out of the record around 1700 and never comes back.

Joke

The outage was contained to a region we didn't know we had customers in.

Something genuinely interesting (and mostly unknown)

On the night of Saturday 10 November 1979, at 23:53 local time, a Canadian Pacific freight train — 106 cars long, three diesel locomotives, moving east through the city of Mississauga, Ontario — threw an overheated journal bearing on the thirty-third car behind the lead unit. The axle cut. The car dropped. Twenty-four cars derailed at the Mavis Road grade crossing on the eastern edge of the city, carrying, among other cargo, eleven cars of liquid propane, four cars of caustic soda, three of styrene, two of toluene, and one of liquid chlorine. A propane car ruptured and ignited. The fireball reached an estimated 1,500 metres and was visible from downtown Toronto, 25 kilometres east.

Over the following six days, approximately 218,000 people were evacuated from an area of about 125 square kilometres covering most of Mississauga and parts of Oakville and Etobicoke, driven out principally by the risk that the intact-but-fire-bathed chlorine tank car in the pile would rupture downwind of residential neighbourhoods. It remained the largest peacetime civilian evacuation in North American history until Hurricane Katrina in 2005, which displaced approximately 1.3 million people from the Gulf Coast. The number of deaths from the Mississauga derailment was zero. The number of serious injuries, reported in the single digits, was almost entirely among first-responders and railway crew caught by the first propane detonation.

The ignited propane cars burned continuously for the next three days. Mississauga Fire, Peel Regional Police, the Ontario Provincial Police, and Canadian Pacific hazard crews worked the chlorine tanker to a condition at which it could be transferred, car-by-car under water cooling, to a siding and offloaded through a pre-prepared chlorine scrubber. The last residents were allowed to return home at approximately 15:00 on Friday 16 November.

The Royal Commission report issued the following year — the Honourable Mr. Justice Samuel G. M. Grange's Report of the Mississauga Railway Accident Inquiry, Queen's Printer for Ontario, December 1980 — ran to 325 pages, examined 123 witnesses over 61 sitting days, and traced the proximate cause to a journal bearing on the thirty-third car that had been inspected visually at the CP Agincourt yard three hours earlier and passed. The failure mode was a hot box: a plain-bearing journal running without adequate lubricant, overheating until the brass bearing shoe seized against the steel axle and cut it. Grange's most-cited recommendation — that trainside hot-box detectors, capable of reading every passing axle, be installed at a maximum spacing of twenty-five kilometres on all Canadian main-line railways carrying hazardous materials — was implemented by Canadian Pacific and Canadian National within four years. The equivalent U.S. retrofit under the Federal Railroad Administration's hazardous-materials inspection rules did not follow for over a decade.

Primary sources:

Grange, S. G. M. Report of the Mississauga Railway Accident Inquiry. Toronto: Queen's Printer for Ontario, December 1980. Chapter 4 reconstructs the hot-box causation chain, with the Agincourt yard inspection log included at p. 83; Appendix D is the hour-by-hour evacuation timeline.
Canadian Transport Commission, Railway Transport Committee. Report on the Derailment of CP Rail Train 54 at Mississauga, Ontario, 10 November 1979. Ottawa, 1980. The operational investigation, with the car-by-car inventory of the twenty-four derailed cars and the sequence of ignition events.
Scanlon, Joseph. "Help in Time of Disaster: The Mississauga Evacuation." Emergency Planning Digest, Ottawa, 1979–1980. Carleton University's Emergency Communications Research Unit field report from inside the Peel Regional Police command post during the evacuation; the one-page handwritten evacuation map used for the first thirty-six hours is reproduced in the text.

A dev fact for the back pocket

Inside every Commodore Amiga shipped between July 1985 and April 1994 sat a chip-level coprocessor that executed a three-instruction programming language, synchronised to the video raster beam, with the entire program re-run from the top on every vertical blank. Its name was the Copper. It lived inside the custom chip "Agnus" (later Fat Agnus, Super Agnus, Alice), designed by Jay Miner's team at Amiga Corp. between 1982 and 1985 for the Amiga 1000. The three instructions were:

WAIT — block until the raster beam reaches a given (x, y) screen position.
MOVE — write a 16-bit value to one of the 256 custom-chip registers mapped at $DFF000–$DFF1FE.
SKIP — conditionally skip the next instruction based on the raster beam's position.

The utility of a three-instruction coprocessor is that you can rewrite the display hardware's configuration in the gap between one scanline and the next. The Amiga's base video modes offered thirty-two colours drawn from a 4,096-colour palette; by assembling a Copper list that waited for each scanline boundary and MOVEd a new palette entry into register $DFF180, a programmer could render a smooth gradient across all 4,096 displayable values on a single screen. The same mechanism could switch display resolution mid-frame, mix lo-res with hi-res playfields in different horizontal strips of the display, run the eight hardware sprites as Copper-moved mouse pointer and HUD elements without CPU intervention, and produce the characteristic raster-bar scrolltext backgrounds of the Amiga demoscene.

The Copper's instruction fetch used Agnus's DMA channel 7, which stole cycles from the Motorola 68000 CPU on alternate memory accesses. The CPU could, in a worst case, lose up to half its bus bandwidth to the Copper on a scanline where the Copper list was dense. This was architecturally accepted. Nothing with a comparable mechanism was shipped on the PC, Macintosh, or Atari ST hardware of the same era, and the trick has no modern GPU equivalent — raster-interrupt palette changes are not a feature any post-2000 display pipeline exposes, because framebuffer-plus-shader won. The last mass-market machine to ship with a Copper descendant was the Amiga 1200 in October 1992, carrying the AGA chipset's Alice. Commodore filed for bankruptcy on 29 April 1994.

Primary sources:

Commodore-Amiga, Inc. Amiga Hardware Reference Manual, Third Edition. Reading, MA: Addison-Wesley, 1991. ISBN 0-201-56776-8. Chapter 7 specifies the three Copper instructions and the DMA timing diagram; Appendix A lists the 256-register memory map.
Mical, R. J., and S. Deyl. "Intuition: The Amiga User Interface." In Commodore-Amiga, Inc., Amiga ROM Kernel Reference Manual: Libraries and Devices. Reading, MA: Addison-Wesley, 1986. ISBN 0-201-11081-4. The system software's model for arbitrating Copper access between the kernel's sprite driver and user programs.
Haynie, Dave (dir.). The Deathbed Vigil, and Other Tales of Digital Angst. Documentary film, West Chester, PA, 1994. Jay Miner's own commentary (approximately 00:42:00) on the Copper's design origin at Amiga Corp. and the alternatives considered.

Today's goal

Finish one glass of water, friend. The whole glass, in a single sitting, without putting it down between the first sip and the last. Watch it until the last drop pools at the bottom. The last drop is the point of the exercise — most of the glasses of water you drink in a month end with the glass left on the counter two-thirds full, forgotten by lunch. Finish one.

Today's toy is the supernaculum — a glass you tilt with a slider. Pour until all but one drop remains, then upend it on the nail and see whether a single drop rolls off. Lives in the corner.

Go drink the last drop.

— C