The Mug Ring Survey

The instituteFounded 1994
Staff of three
Office, Egnatia Street

Three surveyors, one pencil, sixty-one offices

The Survey began in 1994 in a back office on Egnatia Street, after an argument about who had ruined a walnut desk. Nobody could prove anything, so K.P. drew a map of the rings, and the argument was over by the next morning. We have been drawing them since.

We work after hours, with the owner's written permission and a red headtorch. Every ring left by a cup is fixed to the nearest millimetre, contoured at 10 microns and given a name approved by the Names Committee. The Names Committee is K.P., on Thursdays.

A ring is treated as terrain. Its rim is a ridge. Its middle is a lake if it sits below mean desk level. Anything sticky is a mountain until a sample proves otherwise.

Offices on file: 61
Sheets published: 212
Named features: 4,907
Deepest lake: −44 µm
Highest summit: 142 µm
Mugs moved during a survey: 0

Survey Manual6th edition
Chapter 4
House style

House style: Greek coffee and filter coffee

The two are never mapped the same way. These rules are from chapter 4 of the Survey Manual, and they are not reopened at lunch.

Symbol set G

Ellinikós, Greek coffee

Grounds are scree. They are stippled and never contoured, because a heap of wet grounds has no honest height.
The foam, kaimaki, dries to a faint inner ring. It is drawn dotted and named only if it is still there in the morning.
The cup is small, so the ring is small. Anything under 6 cm across is named in the plural, as a group of tarns, in case it multiplies.

Symbol set F

Filter coffee (fíltro)

Contoured at 10 microns, with a heavier index contour every 50.
The rim is always a ridge. The middle is a lake below mean desk level and a plain above it.
Milk softens the rim. We record the milk. We do not ask about the milk.

Frappé was invented in this city in 1957 and is mapped as a delta, because the glass sweats. Tea is outside our remit and is passed to a colleague in Patras.

Gazetteer14 entries
Revised Sept. 2026
Yours in pencil

Gazetteer of named features

Every official name on the published sheets. Grid references are six figures, good to one centimetre. Height is the highest point above mean desk level; for a lake it is the deepest point below it. Rings you survey on the sheet above are added at the bottom, in pencil, until the Committee meets.

Search the gazetteer 14 features

Name	Feature	Sheet	Grid ref	Height, µm	Surveyed	By
Lake Espresso	lake, filter coffee	7	342 171	−38	14 Mar 2019	K.P.
Crema Ridge	ridge, filter coffee	7	351 164	91	14 Mar 2019	K.P.
Mount Sugar-Spill	summit, sucrose on filter	7	357 184	142	9 Nov 2022	Th.D.
The Frappé Delta	delta, frappé condensation	12	118 044	22	2 Aug 2021	A.M.
Kaimaki Tarns	tarns, Greek coffee	19	071 233	−12	30 Jan 2020	A.M.
Katakathi Screes	scree, Greek grounds	19	074 229	64	30 Jan 2020	A.M.
Monday Moraine	moraine, mixed	3	210 090	47	7 Sep 2015	K.P.
Deadline Tarn	tarn, espresso	12	131 052	−21	18 Dec 2023	Th.D.
Saucer Col	pass, filter coffee	7	347 168	33	14 Mar 2019	K.P.
Glyko Heights	ridge, Greek, sweet	22	402 118	77	5 May 2024	A.M.
The Lungo Narrows	channel, espresso	31	015 061	−9	11 Oct 2025	Th.D.
Reply-All Basin	basin, filter coffee	12	124 047	−44	3 Apr 2024	K.P.
Biscotti Spur	spur, filter and crumbs	31	022 070	58	11 Oct 2025	Th.D.
Old Walnut Rim	ridge, the first one ever mapped (desk since sold)	1	000 000	36	12 Feb 1994	K.P.

Surveyors: K.P., chief. A.M., Greek coffee. Th.D., nights and weekends. You: provisional, in pencil.

Field methodsNight work only
19:40 to 23:00
One pencil case

Field methods

All survey work happens between 19:40, when the cleaners leave, and 23:00, when the building turns off the corridor lights. The kit fits in one pencil case, and the pencil case has never been surveyed.

The kit

Theodolite, pencil patternA 2B pencil pivoting on a 180° protractor. Reads to half a degree under a headtorch.

Steel rule, 300 mmMeasures the baseline twice. Never used to scrape anything, whatever the temptation.

Scale biscuitPlain, 66 mm across. Appears in every photograph. Eaten only after the sheet is signed.

Headtorch, red filterRed light keeps the surveyor's night vision and does not bring the security guard upstairs.

How a ring is fixed

Wait for the cleaners to leave. Log the time. It is usually 19:40, later on Fridays.
Take the two ends of the keyboard and the monitor foot as fixed points. Nobody moves them without a written request.
Measure the baseline between the keyboard ends with the steel rule, twice. The standard office keyboard gives 44.1 cm.
From each end of the baseline, sight the centre of the ring with the pencil theodolite and read the angle to half a degree.
Draw both bearings on film. Where they cross is the ring. A third bearing from the monitor foot checks it, and if the three disagree by more than 2 mm, someone has been wiping.
Feel the rim profile with a fingertip, calibrated each evening against one sheet of 80 gsm paper, which is 100 microns thick.
Propose a name. Wait for Thursday.

The scienceDeegan et al.
Nature, 1997
Capillary flow

Why the rim is darker

A drying drop stays pinned at its edge, and the edge dries fastest, so liquid keeps flowing outward from the middle to replace what evaporates there. That flow carries the coffee with it and leaves most of it in a thin, dark line at the rim.

Drying time 00:00 of 20:00 0% at the rim

Left, the drop from above. Right, the same drop in section. Blue ticks are evaporation, arrows are flow. 900 particles, drawn about a thousand times too large.

Deegan, Bakajin, Dupont, Huber, Nagel and Witten, "Capillary flow as the cause of ring stains from dried liquid drops", Nature 389, 827-829 (1997). Make the particles oval instead of round and the ring mostly goes away (Yunker and colleagues, Nature, 2011). The Survey has read that paper and has decided not to discuss it.

SalesPosted Tuesdays
Folded or flat
Film, 75 microns

Map sheets for sale

Printed on 75 micron drafting film and folded by hand into eight panels, which is two more than anyone can refold. Each sheet comes with its gazetteer extract and a stamped card for reporting new rings.

Sheet 7, Accounts Department

Lake Espresso, Crema Ridge and Mount Sugar-Spill.

€6.40 folded · €9.00 flat, in a tube

Sheet 12, Meeting Room B

The Frappé Delta, Reply-All Basin and Deadline Tarn.

€7.20 folded · €9.80 flat, in a tube

Sheet 31, The Night Desk

The Lungo Narrows and Biscotti Spur. The desk is being replaced in November, so this edition is the last.

€5.80 folded