tempering air

tempering air

[′tem·pə·riŋ ‚er]
(engineering)
Low-temperature air added to a heated airstream to regulate the stream temperature.
References in classic literature ?
It was now the height of summer, and these naked plains would be intolerable to the traveller were it not for the breezes which swept over them during the fervor of the day, bringing with them tempering airs from the distant mountains.