"That is right. Every child soon learns by experience to make a practical distinction of this kind. He very soon understands that he can hold a stick of wood without burning his hand, even though it be blazing at the other end, but that when a piece of iron is red hot at one end he must not take hold of it at the other. The child very soon learns to know the different feeling of a cotton night-gown from one of flannel, and the difference in apparent warmth between a linen pillow-case and a woolen blanket. After a room has been heated for a considerable time the various objects in it all become of the same temperature, and the same is true in a cold room; but how great the difference in the sensations produced by touching the oil-cloth and a woolen carpet in a cold room! Good conductors of heat, if hot, feel very hot; or if cold, feel very cold; while poor conductors make a much less decided impression. Why is this, Samuel?" "The good conductors receive heat or part with it very readily. If the good conductor be hotter than our bodies, it imparts its heat rapidly to our hand, and because we receive heat rapidly from it, it feels to us very hot. Or if it be colder than our bodies, it takes heat from our hands very rapidly, and gives the impression of being very cold. Poor conductors impart heat to the skin or take it away more slowly, and hence feel as if their temperature were more nearly like that of the body." "The conducting qualities of bodies," said Mr. Wilton, "seem to depend chiefly upon their structure or the arrangement of their atoms. Bodies which are compact and solid in their structure convey heat more rapidly than those which are loose and porous. Hence solids are better conductors than fluids, and fluids are better conductors than gases, and among solids the metals are better conductors than organized bodies, like wood or flesh, and better than the loose and porous minerals. In bodies of loose, porous, or fibrous texture, the continuity of the conductory substance is constantly broken. The particles in a mass of sawdust touch only at a few points, leaving frequent spaces. In woolen and cotton fabrics the points of junction of the fibres are very few, comparatively. For this reason the motion is not readily communicated from atom to atom.