Jordan sunshine recorder

A sunshine recorder of the type in which the timescale is supplied by the motion of the sun.

It consists of two opaque metal semicylinders mounted with their curved surfaces facing each other. Each of the semicylinders has a short narrow slit in its flat side. Sunlight entering one of the slits falls on light-sensitive paper (blueprint paper) that lines the curved side of the semicylinder. One semicylinder covers morning hours, the other afternoon hours. The sensitivity of the recording paper is variable, and this introduces an uncertainty in the evaluation of the record.

Light from the sun;