The Immersion Cistern of Entry hall 643 was an oval pool six paces long, hewn directly from a massive burl of stone-hard cedar and lined with smooth, water-worn river stones of green chlorite.
The pool was filled with crystal-clear stone salt water heated to forty-one degrees by earth-heat channels beneath the floor. Floating upon the surface of the steaming water was a glowing layer of the singing tree-marrow. Two quarts of the rainbow-bright, jade-green distillate that hummed softly at four hundred and forty hertz, filling the warm chamber with the ancient scent of mountain pines and wild honey.
Around the outer edge of the water tank ran four fluted cedar handrails, worn smooth by hundreds of years of convalescent hands. everyone could feel the clean, eucalyptus-scented steam, fully empty of the sharp sulfur bite that poisoned the lower rifts. Along the stone curbs stood shallow clay pot basins filled with crushed dried herbs, healing clays, and squares of bleached linen.
The green chlorite stones paving the bottom of the vat had been gathered from underground riverbeds ten leagues to the west. Rich in magnesium and stone-glass minerals, they acted as natural heat charge banks, storing the earth-heat and streaming it upward into the bathers’ limbs in steady, deep-piercing infrared waves.
