Page:Taine - Le Positivisme anglais, 1864.djvu/93

Le texte de cette page a été corrigé et est conforme au fac-similé.

chaude, pendant que leur surface extérieure est très-froide[1].

  1. The conclusion obtained by this new application of the method is, that, cœteris paribus, the deposition of dew is also in some proportion to the power of radiating heat ; and that the quality of doing this abundantly (or some cause on which that quality dépends) is another of the causes which promote the deposition of dew on the substance.

    “Again, the influence ascertained to exist of substance and surface leads us to consider that of texture : and hère, again, we are presented on trial with remarkable differences, and with a third scale of intensity, pointing out substances of a close firm texture, such as stones, metals, etc., as unfavourable, but those of a loose one, as cloth, velvet, wool, eiderdown, cotton, etc., as eminently favourable to the contraction of dew. The Method of concomitant Variations is here, for the third time, had recourse to ; and, as before, from necessity, since the texture of no substance is absolutely firm or absolutely loose. Looseness of texture, therefore, or something which is the cause of that quality, is another circumstance which promotes the deposition of dew ; but this third cause resolves itself into the first, viz. the quality of resisting the passage of heat : for substances of loose texture are precisely those which are best adapted for clothing or for impeding the free passage of heat from the skin into the air, so as to allow their outer surfaces to be very cold, while they remain warm within.”