IN a note on domestic heating (NATURE, July 6, p. 16) it is said, ” ;We do not agree with Prof. Bone that a chimney is necessary for the suitable ventilation of bed and living rooms”, and add, ” Many systems fur ventilating rooms have been devised”. Now, the nature of the radiations which arc used to heat a room have been shown to be of much importance. Dark and dull red heat, in the absence of cool moving air, give stuffy feelings and by congesting the nasal membrane lessen the air-way, as proved by me and confirmed by Dr. W. A. R. Thomson, and by Dr. Dishoeck of Groningen, while bright sources have tho opposite effect in about 50 per cent of those observed.