Not yet revealed
charge unit
System term
The unit in which a collar’s breathing demand is reckoned, drawn from the cartridge fitted in the band, each of which carries a small gauge. Breathing underwater costs three units a minute, and the rule is that nobody goes under the lintel without enough charge for three crossings. Spent cartridges are replaced with fresh ones, left to settle before use.
Also appears in Chapter 4, A Road for Going Under.