It is used to measure the daily global solar radiation. The censor is composed of three bimetallic plates of equal size comprising two metals of different coefficients of thermal expansion. The central layer is blackened with a painting of high absorbent power, consequently laminating black rather than white, warms this difference in temperature that is approximately proportional. It has a pen inscriptora that recorded on a strip of paper produced displacement, this is placed on a drum which revolves to speed through a system of watchmaking. Everything is protected by a metal box that has a transparent global radiation hemispherical Dome, below the censor and the disc that has an object prevent the passage of the radiation inside the actinógrafo, you must install perfectly horizontal, the hemispherical dome is geared up to receive radiation in a solid angle of 180 ° sensitive or bimetallic surfaces are oriented in the East-West direction to the North for stations in the northern hemisphere and towards the southern hemisphere.