Weather forecaster, Negretti and Zambra, 1915

Weather forecaster device, patent no. 6276, by designed by E. W. Kitchin and modified and improved by Negretti and Zambra, London, UK 1915. Inscription: ‘Directions: Observe direction of wind, read barometer and note whether rising, falling or steady. Set dials accordingly and the forecast appears where indicated. Arrow points between two forecasts, combine the two. When temperature low enough, for rain read snow. Winter, October – March inclusive. Summer, April – September inclusive.’

Simple forecasters like this, made weather prediction easy and accessible; in their catalogues, maker Negretti and Zambra argued this device would be ‘Invaluable to motorists, golfers, hunting men, and all outdoor sportsmen’. The user just needed access to a barometer (Negretti and Zambra recommended an aneroid barometer), and then by rotating the brass discs a forecast could be read directly from the instrument. Before powerful computers became available after the Second World War, enabling the development of numerical weather prediction, weather forecasts were derived from a body of meteorological knowledge and laws.