has been the approved supplier of Stevenson Screens to the South African Weather Bureau and other research institutions since 1973.
Thomas Stevenson (1818-1887) – a Civil Engineer and father of author Robert Louis Stevenson – is accredited with the design of the Stevenson Screen, which is still widely used today. He is also famous for inventing a new and much improved illumination system for lighthouses.
The screen is designed to protect the thermometers from the effects of direct radiation and precipitation, whilst allowing the free movement of air through the screen. The screens manufactured by H & S Timbers are constructed from kiln dried Eucalyptus Saligna finished off with three coats of epoxy strontium chromate primer followed by two coats of white polyacrythane.
The front, back and side panels are doubled louvred with the outer louvre sloping downward and outward. The door has solid brass hinges at the base allowing it to hinge downward to the vertical position. When closed, the door can be locked using a solid brass hasp and staple. Three partially overlapping floorboards are fitted with the outer two sloping downward to allow rainwater to run off. Took clips are fitted to allow easy fitting and removal of the thermometers. To offer maximum protection from the elements, the screens are fitted with a white Glass Reinforced Plastic (GRP) roof.
Stevenson Screens are usually supported by means of a steel stand, which is firmly set in the ground. To comply with Meteorological Office Standards, the stand ust elevate the screen, so that the bulbs of the wet and dry thermometers are 1.25m above the ground. These stands are available in knock down form.