“ However, the truth that the spacers will conduct some heat usually leads in chilly weather to the formation of temporary, grid-shaped patterns on the floor of an evacuated window, consisting both of small circles of inside condensation centred around the spacers, the place the glass is barely colder than common, or, when there may be dew outdoors, small circles on the exterior face of the glass, by which the dew is absent as a result of the spacers make the glass close to them slightly warmer. ”