31. Hygrometer not to be affixed to wall, etc., unless protected by wood.
(1)No hygrometer shall be affixed to a wall, pillar or other surface unless protected therefrom by wood or other nonconducting material at least half an inch in thickness and distant at least one inch from the bulb of each thermometer.(2)No hygrometer shall be fixed at a height of more than 170 centimetres from the floor to the top of thermometer stem or in the direct droughts from a fan, window or ventilating opening.
