Soot-figures on Ceilings

Abstract

THE soot-figures on ceilings described by Mr. Poulton remind me of the appearance of very similar figures brought out by hoarfrost. The first time I noticed this effect was on the surface of a smoothly-boarded gate, where the parts behind which the bars of the framing ran were marked out by a much thicker coating of hoar-frost than the rest. Subsequently I noticed the same effect on a wooden pier where the planking was crossed by broad belts of white, exactly outlining the timbers to which the boards were nailed. On another occasion thick hoar-frost had formed on the roof of the after-cabin of the steam yacht Medusa, composed of a close pile of fine needles of ice about one-eighth of an inch high, inclined at various angles. At first the places where the thin teak boards were nailed to the cross-beams were covered only a little more thickly than the rest, but as the warmth of the day increased the ice spicules disappeared—evaporated rather than melted—from the unsupported parts, but remained in a broad band outlining each beam except above the nail-heads, over each of which a small clear space had melted.