plumming

1. 1
   verb

   Present participle and gerund of plum.

   Note

   The -ing form of a verb that is simply another spelling of plumb. Plumming therefore means plumbing and has nothing to do with the fruit that the noun plum names. The final m doubles before -ing, as in drumming. Used as a noun, the gerund names the activity itself, and miners gave that activity a fixed meaning of their own in the mine-surveying sense.

2. 2
   noununcountable

   Compass work in a mine that finds where to sink an air shaft, where to drive a tunnel to the workings, or which way the lode tilts.

   Careful plumming showed the captain exactly where to sink the air shaft.

   After a day of plumming, the surveyor marked the line for the new adit.

   Similarsurveying

   Note

   Mining took the ordinary verb plum, "to plumb" and made its gerund a trade term. The instrument is the mine dial, a compass, so the "plumbing" here is done by taking bearings rather than by hanging a weighted line. The word is uncountable: a surveyor does plumming or spends a day at it, but never makes a plumming.

3. 3
   noununcountable

   A plum-colored discoloration that distorts the appearance of photographic prints.

   Years of poor storage left visible plumming across the family portraits.

   The technician spotted plumming in the prints and traced it to exhausted fixer.

   Note

   A photographer's word built on the color rather than on the verb. Here plum is the fruit, and the name describes tones that drift toward its dark reddish purple. That makes it a different word from the miners' compass work, though the two are spelled the same. Like a stain, it is uncountable: a print shows plumming, or some plumming, and the cause is a chemical or processing fault.

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