A Comparative Study of the Sunshin Recorders of Campbell-Stokes and Jordan

When the glass sphere and recording papers after Campbell-Stokes are wetted so much with dew or frost and the morning sunlight is so feeble that it is incapable to give burning traces on the recording paper, the registered sunshine hours are found to be of shorter duration than they ought to be. The comparison was made between the Sunshine recorders of Campbell-Stokes and those of Jordan from Mar to Feb. at Kashiwa, a little suburban town near Tokyo. The mean reterdation of Campbell-Stokes' sunshine recorder as Compared with Jordans' in the fine morning is as follows:— 0.22 hours when dew or frost is light 0.34 hours when dew or frost is moderate 0.45 hours when dew or frost is heavy This Phenomenon is not outstanding, though naticeable, in Tokyo, Compared with Kashiwa, because these apparatuses mount on the high tower in Tokyo, while those at Kashiwa are Placed near the ground. The following remarks will be warthy to note. 1) Campbell-Stokes recorder reacts more sensitively to sunshine than Jordan's in sunset and sun rise, and also in dense haze. 2) Jordan's recorder registers Prettily well even when the sunlight is screened with thin clouds.